i need help with solving polynomialequations like so: (d-7)(d+4/3)=0

- anonymous

i need help with solving polynomialequations like so: (d-7)(d+4/3)=0

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- anonymous

(a+b)(c+d)=ac+ad+bc+bd

- anonymous

but d is the same so how would d=c?

- anonymous

if d is a how could it be C?

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## More answers

- anonymous

d={7, -4/3}

- anonymous

do i distribute?

- anonymous

no, it's already factored

- anonymous

hmmm, ok, like this:
(x+y)(u+v)=xu+xv+yu+yv
apply this into your equation
x=d, y=-7, u=d, v=4/3

- anonymous

no way ttt, d can't equal -7, that makes the equality false!

- anonymous

im solving it it will =0 like this, (x-4)(X+2)=0 so x-4=0 and x+2=0

- anonymous

so x=4 or x=2

- anonymous

but i dont get it

- anonymous

what don't you get?

- anonymous

oh dear =))
d=7
d=-4/3
something wrong with my head just now lol

- anonymous

howdoes x=4 when it is x-4=0

- anonymous

if you add 4 to both sides of the equation x - 4 = 0 you get x = 4

- anonymous

so for my first equation d-7=0 and d+4/3=0?

- anonymous

exactly

- anonymous

exactly

- anonymous

what do i do from there i add -7 and 4/3 to each side?

- anonymous

no, you add 7 and subtract 4/3

- anonymous

thats what i meant thanks alot for your help tho

- anonymous

no problem

- anonymous

what would my answer be if they both =0 would it be d=0?

- anonymous

they both don't equal 0, only one at a time

- anonymous

wait so i do 4/3-d or 0

- anonymous

or 4/3-0*

- anonymous

?

- anonymous

what would i do -7+d or -7+0???

- anonymous

what? d is two distinct answers
d ={7, -4/3}

- anonymous

but if d-7=0 and d+4/3=0 what would i do then

- anonymous

hi people :P

- anonymous

samarrel?

- anonymous

that means that d has two solutions 7 and 4/3

- anonymous

hey people who wants to play uno

- anonymous

so thats my answer?

- anonymous

sam?

- anonymous

anyone?

- anonymous

(d-7)(d+4/3)=0
d-7=0, d=7 because 7-7=0
d+4/3=0, d=-4/3 because -4/3+4/3=0
which part don't you understand? dont make it too complicated.

- anonymous

wouldnt it be 7+7?

- anonymous

why would it be 7+7?
d=7, so you change letter d in the equation into number 7. you didn't touch the minus sign at all so how can it become +

- anonymous

because d-7=0 add 7 to each side right?

- anonymous

ohhh ok i get it if it = 0 than it would be corect right?

- anonymous

that's what people always do, I dont. why add more stuff? think this way. you have 7 on the right, now change it to the left. everytime you change side of anything, you change the sign. that number 7 on the left, you have - before it, so it's -7. now you move -7 to the left, you change the sign. So -7 on the right become +7 on the left. done

- anonymous

now try this, a-6+12=2, lets see if you get it right.

- anonymous

hmm

- anonymous

idk do i add 6 to each side?

- anonymous

no no, dont add anything, move it to the other side. what you have on the left? you have (-6) and (+12) right? so change the side. remember, CHANGE SIDE, CHANGE SIGN. (-6) from left to right become +6, +12 left to right be come -12.
can u do the rest now?

- anonymous

a-12=2+6?

- anonymous

that 12 there, why is it still on the left. It should be changed to the right to become -12.
a=2+6-12
like that
try another one
x+5-7=1
remember, if you change its side, also change its sign, if not, nothing happen

- anonymous

x=1-5+7?

- anonymous

absolutely right.
how about 5-9=7-x

- anonymous

-7+5-9=x

- anonymous

should be -x, because -x wasn't changed side, right?
-7+5-9=-x
u understand this part?

- anonymous

ohh ok yea

- anonymous

so I think you get it now.
back to the problem, you have d-7=0 or d+4/3=0
just do the same, change side, change sign.

- anonymous

0=7+d?

- anonymous

???
no, keep d in one side, push everything else to the other side, because you're finding d here.
do again?

- anonymous

ohh ok because im ffinding d it would be 0+7=d?

- anonymous

that's alright, but you just begin with this method, so try follow the rule
d-7=0
-7=-d (see, change side, change sign)
d=7 (again, change side, change sign)

- anonymous

if you move anything from left to right or right to left, change the sign that go with it.
eg. -7 on the left becomes 7 on the right
or x on the right, become -x on the left

- anonymous

oh ok

- anonymous

bla bla bla

- anonymous

d+4/3=0 ?
d=?

- anonymous

-4/3+0=d

- anonymous

my aint used to make me do this stuff for the whole day. she's a teacher

- anonymous

that's ok but you shouldn't do it that way because it could easily get wrong.
you have d+4/3=0
what you wanna find should be on the left, so d stay.
4/3 on the left, moved to the right, becomes -4/3
so d=-4/3

- anonymous

i want to do this stuff all day just dont have the stuff to do it so my friend aarman who is great on this site showed me it so i come on here

- anonymous

what happend to 0?

- anonymous

lol, 0 is nothing, just thought it away. anything add up with 0 become itself.
right, can you solve this:
d-1/4+5=0
remember, d stay, everything else go.

- anonymous

throw* lol

- anonymous

d=-1/4-5?

- anonymous

you forgot to change sign of -1/4. can you see that mistake?

- anonymous

on the left, it's -1/4, so on the right, what should it be?

- anonymous

1/4-5

- anonymous

that's right.
I'm gonna go to sleep now, but try this last one first.
-4d+5-3+12=1-7d+2/3
remember bring all the d to the left and all the number to the right.
and do slowly step by step, no rush

- anonymous

1+4-5+3-12=d

- anonymous

not really, you know left and right right? (left)=(right)
look at the term d first,
we have -4d on the left, so keep it, -7d on the right, bring it to the left, change the sign, become 7d.
so on the left you have -4d+7d
on the right, there's 1 and 2/3, keep them. there're +5-3+12 on the left, bring them to the right, change sign, become -5+3-12
so the right: 1+2/3-5+3-12
then equation is
-4d+7d=1+2/3-5+3-12
compare these two:
-4d+5-3+12=1-7d+2/3 (origin)
-4d+7d=1+2/3-5+3-12 (after changing)
I'll put some brackets for clarity
-(4d) + 5 -3 +12 = 1 -(7d) +2/3 (origin)
-(4d) +(7d) = 1 +2/3 -5 +3 -12 (after changing)

- anonymous

ok man, I'm gonna go, but this will help you
http://www.mathexpression.com/solving-linear-equation.html
watch the video :)

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