anonymous
  • anonymous
solve by elimination 0.3x-0.2y=4 0.4x+0.3y=-1
Mathematics
chestercat
  • chestercat
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your free account and access expert answers to this
and thousands of other questions

amistre64
  • amistre64
muliply by 10 to get rid of the decimals... that will make it look less intimidating
amistre64
  • amistre64
3x-2y = 40 4x +3y = -10
yuki
  • yuki
if you multiply 40 on the first eqn and 30 on the second, you can see which ones can be eliminated

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

yuki
  • yuki
your idea is to make the coefficients of either x or y to be equal
yuki
  • yuki
for most elimination problems, that will work
amistre64
  • amistre64
to eliminate the x variables; *4 the top and *3 the bottom...then subtract
amistre64
  • amistre64
12x -8y = 160 12x +9y = -30
amistre64
  • amistre64
we could combine these steps by mulitply one equation by a negative instead... 12x -8y = 160 -12x -9y = 30 --------------- -17y = 190 y = -190/17
anonymous
  • anonymous
you lost me
amistre64
  • amistre64
where?
anonymous
  • anonymous
12x-8y=160 12x-9y=-30 how did you get those
amistre64
  • amistre64
by subtraction...... 12x -8y = 160 12x -8y = 160 -(12x +9y = -30) means -12x -9y = 30 ---------------- ----------------
amistre64
  • amistre64
tell me: does this equal out? 5 5 -(-4) +4 ---- ---- ???
anonymous
  • anonymous
yes
amistre64
  • amistre64
thats all i did..... just with more numbers involved
anonymous
  • anonymous
how did you get the 12x -8y = 160 & -(12x +9y = -30)
amistre64
  • amistre64
elimination means 'get rid of something'...right? the only way to get rid of something; to eliminate it; is to get it to zero... otherwise there is something still there right?
anonymous
  • anonymous
right
amistre64
  • amistre64
you are given 2 equations and are asked to eliminate something.... that would either be the xs or the ys right? I choose the xs cause they were in front.
anonymous
  • anonymous
ok
amistre64
  • amistre64
do you recall that in an equation..whatever you do to one side has to be done to the other to keep it equal?
anonymous
  • anonymous
yes
amistre64
  • amistre64
5+3 = 8 when we multiply this by 4 is it still equal? 4(5+3 = 8)..... 20 + 12 = 32 ???
anonymous
  • anonymous
right
amistre64
  • amistre64
do the variables make a difference to it? 4(5x + 3y = 4)......20x +12y = 16...still equal??
amistre64
  • amistre64
we are not changing the 'value'...just the form, its shape, the way it looks..... the value remains the same. right?
anonymous
  • anonymous
right
amistre64
  • amistre64
so lets use this to our advantage.. we want some part of your equation to cancel each other out... what wer ethe equations again?
amistre64
  • amistre64
0.3x-0.2y=4 0.4x+0.3y=-1 we can multiply both equation by 10 to get rid of the decimal and make it easier to look at right? we change the shape; but not the value
anonymous
  • anonymous
k
amistre64
  • amistre64
3x - 2y = 40 4x +3y = -10 we good here?
anonymous
  • anonymous
yes
amistre64
  • amistre64
we have no terms that are the same...so we have to modify some more..... to get rid of one of them.....or rather a set of them.
amistre64
  • amistre64
if we pick 'x'...what value do 4x and 3x have in common?
anonymous
  • anonymous
x?
amistre64
  • amistre64
x is not a 'value' :) 4x and 3x..... do they have 12x in common? 8x? 29x?
amistre64
  • amistre64
x is a valued pick; but that makes things messier lol
amistre64
  • amistre64
valid pick is what its spose to say...
amistre64
  • amistre64
4x(3) = 12x 3x(4) = 12x.....right?
anonymous
  • anonymous
right
amistre64
  • amistre64
so the top can be *4; and the bottom *3 4(3x - 2y = 40) 12x -8x =160 3(4x +3y = -10) 12x +9y = -30 havent changed anything but the way they look correct?
anonymous
  • anonymous
correct
amistre64
  • amistre64
but if we add these together...nothing is eliminated is it?... what do we have to do to get an elimination now?
anonymous
  • anonymous
wouldnt x be eliminated
amistre64
  • amistre64
how? 12x + 12x = 24x..... that aint zero..
anonymous
  • anonymous
your right i was thinking bout -12x +12x continue plz
amistre64
  • amistre64
thats right... we need to change the way one of them looks again to get a -12x... 12x -8x =160 12x -8x =160 -1(12x +9y = -30) -12x -9y = 30..now were good to go
amistre64
  • amistre64
can we eliminate now?
anonymous
  • anonymous
yes
amistre64
  • amistre64
we get: -17y = 190..... solve for y y = -190/17. right?
anonymous
  • anonymous
yes
amistre64
  • amistre64
since we have a solid value for y...use it to find x
anonymous
  • anonymous
wait how does 190 become -190 and -17 becomes 17
amistre64
  • amistre64
the negative doesnt care what its attached to..... any (+)(-) combonation results in a (-)...right? does 190/-17 equal something different than -190/17?
anonymous
  • anonymous
i guess not
amistre64
  • amistre64
the proper ettiquiette is to put the sign to the top...
amistre64
  • amistre64
but in some cases its good to know that you can move it around
amistre64
  • amistre64
what wouldve hapened aif we combined steps?
amistre64
  • amistre64
.4(.3x -.2y = 4) .12x -.08y = 1.6 -.3(.4x+.3y =-1) -.12x -.09y = .3 ----------------- -.17y = 1.9 y = -1.9/.17 = -190/17
anonymous
  • anonymous
right
amistre64
  • amistre64
0.4x+0.3y=-1 .4x + .3(-190/17) = -1....solve for x
anonymous
  • anonymous
-5.7
anonymous
  • anonymous
or is it -133/17
amistre64
  • amistre64
4x = -10 + 570/17 4x = (-170 + 570)/17 4x = 400/17 x = 400/4.17 = 100/17
amistre64
  • amistre64
4.17 is a lazy way of writing 4*17
anonymous
  • anonymous
how did yiu get 570/17
amistre64
  • amistre64
i used 3(-190/17) instead of .3(-190/17) 3(-190) = -570 ------ ------ 17 17 4x - 570/17 = -10 4x = -10 + (570/17)...
anonymous
  • anonymous
oh ok i was doing it by .3
amistre64
  • amistre64
:) .3 was fine, but you would have had to change the decimal eventually
amistre64
  • amistre64
1/.17 cahnges to 100/17
anonymous
  • anonymous
-10*17=-170
amistre64
  • amistre64
.4x + .3(-190/17) = -1 .4x - 57/17 = -1 .4x = -1 + (57/17) .4x = (-17+57)/17 .4x = 40/17 x = 40/(.4*17) x = 400/(4*17) x = 100/17
anonymous
  • anonymous
ok i think i got it
amistre64
  • amistre64
i think i see you trying to get rid of the 17 on the bottom :)
anonymous
  • anonymous
i just dont know how to do this stuff
anonymous
  • anonymous
taking midterms this week these questions are for the practice exam
amistre64
  • amistre64
68x - 570 = -170 68x = -170 + 570 x = 400/68 x = 400/4 100 ------- = ----- 68/4 17
amistre64
  • amistre64
i got a final grade of 89.06%...and it gave me an 'A' for the course ;)
amistre64
  • amistre64
i dropped 3 writing assignments and still passed with an 'a' lol
anonymous
  • anonymous
thats good! right now i have a 77.37%
anonymous
  • anonymous
how did you get those answers above 68x....
amistre64
  • amistre64
i times everything by 17 to get rid of the fraction...
amistre64
  • amistre64
4(17) = 68
anonymous
  • anonymous
right but 3(17)=51
amistre64
  • amistre64
3(-190)(17) ---------- = 3(-190) (17)
amistre64
  • amistre64
17/17 = 1
anonymous
  • anonymous
x=400/68 i divide that by?
amistre64
  • amistre64
thats why its called getting rid of a fraction ;)
amistre64
  • amistre64
400/68 has 4 in common..remember 4(17)? and 4(100) = 400
amistre64
  • amistre64
divide them both by 4
anonymous
  • anonymous
ok now that way makes sense to me
amistre64
  • amistre64
you seem to see numbers and math is a solid concrete building that cant be moved or messes with. but its really more like silly putty...bend it to your will :)
amistre64
  • amistre64
algebra has 5 rules: and only 5 rules...
anonymous
  • anonymous
whats that?
amistre64
  • amistre64
1. numbers can be moved around (commutative) 2. numbers canbe grouped in different ways (associative) 3. every number has an evil twin (inverse). 4. there is one number that changes nothing (identity) 5. distribute numbers thru paranthesis (distributive)
anonymous
  • anonymous
i will have to make a note of those
amistre64
  • amistre64
3 and 4 are split in 2 by some people to get an additivie inverse/multiplicative inverse and an additive indentity/multiplicative identity
amistre64
  • amistre64
tell me; the 1st rule says we can move number around... 4-5 is the same as -5+4 right?
anonymous
  • anonymous
yes =-1
amistre64
  • amistre64
-10 + 6 is the same as 6 - 10 right? when you move numbers...pack their luggage, there signs :)
amistre64
  • amistre64
does grouping matter? 3*(4*5) is the same as (3*4)*5 right?
anonymous
  • anonymous
same
amistre64
  • amistre64
3+(5-6) the same as (3+5)-6? but you gotta keep an eye out for this sometimes....
amistre64
  • amistre64
3-5-6 ^ never split a negative/subtractionwith a parenthesis
amistre64
  • amistre64
3+(-5-6) is the same as (3-5)-6
amistre64
  • amistre64
subtraction and division are make believe..... there is only addition and multiplication that is real.
anonymous
  • anonymous
yes=-8
amistre64
  • amistre64
3-5 means 3+-5
amistre64
  • amistre64
5-2 means 5+ -2
amistre64
  • amistre64
the evil twin rule.... accounts for subtraction and division...
amistre64
  • amistre64
what is the evil twin of 15? its -15 the evil twin of -3 .... is 3
amistre64
  • amistre64
the evil twin of 6, when multiplying is 1/6 tho..... thats why some people split the rules
anonymous
  • anonymous
thought it was -6
amistre64
  • amistre64
additions evil twin is the opposite of a number; -9 ; 9 multiplications evil twin is the upside down; 8 ; 1/8
amistre64
  • amistre64
recpirocal is an upside down fraction rigt? the evil multplication twin of 3/4 is 4/3 the evil addition twin of 3/4 is -3/4
amistre64
  • amistre64
the evil addition twin of 18 is -18 teh evil multiplication twin of 18 is 1/18
amistre64
  • amistre64
what is the addition identity number? 4 + ? = 4 -9 + ? = -9 17 - ? = 17
amistre64
  • amistre64
what is the multiplcation identnty number? 6*? = 6 14*? = 14 (-5/8)*(?) = -5/8
amistre64
  • amistre64
when evil twins meet; they form the identity number: 4+ -4 = 0 12 + -12 = 0 -7 + 7 = 0 4(1/4) = 1 2/5(5/2) = 1 (129/17) (17/129) = 1
amistre64
  • amistre64
and rule 5; distribution 5(3+6) = 45 5(3) + 5(6) = 45 15 + 30 = 45 45 = 45
amistre64
  • amistre64
whatever we can distribute together; we can undistribute as well...which is what we cal factoring quadratic equations

Looking for something else?

Not the answer you are looking for? Search for more explanations.