anonymous
  • anonymous
Question 13 (Multiple Choice Worth 5 points) [9.05] What are the exact solutions of x2 − x − 4 = 0? x = the quantity of negative 1 plus or minus the square root of 15 all over 2 x = the quantity of 1 plus or minus the square root of 15 all over 2 x = the quantity of 1 plus or minus the square root of 17 all over 2 x = the quantity of negative 1 plus or minus the square root of 17 all over 2
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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chestercat
  • chestercat
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rob1525
  • rob1525
lol ;)
anonymous
  • anonymous
I think it be D but its not right to me can you help me
rob1525
  • rob1525
so, lets use the difference of squares method (also know as the pathagorian therom) to solve this.

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More answers

rob1525
  • rob1525
\[(-b +or- \sqrt{b^2-4*ac})/2a\]
anonymous
  • anonymous
whats next
rob1525
  • rob1525
so the equation us have has the form a^2-b-c=0
rob1525
  • rob1525
sooo....\[-1+or-(\sqrt{-1^2-4*1*-4})/2*1\]
anonymous
  • anonymous
I don't know how to do this sorry
rob1525
  • rob1525
solve for -1^2-4*1*-4 first...k
anonymous
  • anonymous
I am lost sorry
rob1525
  • rob1525
okay sorry... what does -1^2*4*1*-4=?
rob1525
  • rob1525
opps I meant -1^2-4*1*-4=?
anonymous
  • anonymous
how do i solve for that
rob1525
  • rob1525
-1^2=1 right-4*1which is -4*-4 which =16...so ur left with 17 right?
anonymous
  • anonymous
yea
rob1525
  • rob1525
-1^2 means negative one to the second power. you know that ya?
anonymous
  • anonymous
2 right
rob1525
  • rob1525
-1x -1 = -1^2 = 1
anonymous
  • anonymous
oh ok
rob1525
  • rob1525
k
anonymous
  • anonymous
so the answer is C right
rob1525
  • rob1525
YOUUUUUU GOT IT... NICE JOB.
anonymous
  • anonymous
cool one more thing can you help me on this Question 14 (Multiple Choice Worth 5 points) [9.05] What are the approximate solutions of 2x2 − 7x = 3 rounded to the nearest hundredth? No real solutions x ≈ −0.77 and x ≈ 7.77 x ≈ −0.39 and x ≈ 3.89 x ≈ −3.89 and x ≈ 0.39
anonymous
  • anonymous
I think its A but not sure lol
rob1525
  • rob1525
k..use the pathagorian therom to solve this one too..but u will need a calc for this one
rob1525
  • rob1525
the 3 on the right side of the equation is confusing u hu?
anonymous
  • anonymous
yea
anonymous
  • anonymous
will it B
rob1525
  • rob1525
so just subtract 3 from both sides so that the right side is equal to 0... like this \[2x^2-7x-3=3-3 -> 2x^2-7x-3=0\] see,
rob1525
  • rob1525
now put it in your calc \[-1*-7 +or- (\sqrt{-7^2-4*2*-3})/2*2\]
rob1525
  • rob1525
|dw:1378866860493:dw|
rob1525
  • rob1525
do the plus for your first answer then the negative for your second x value..do u understand?
anonymous
  • anonymous
no not really
rob1525
  • rob1525
soo....what is confusing u?
anonymous
  • anonymous
is it D
rob1525
  • rob1525
I don't have a calc infront of me :(
anonymous
  • anonymous
evening sorry i just start this how do i put it o in the calc
rob1525
  • rob1525
Im glad u asked... ur first x value is \[(7+\sqrt{73})/4\] and the second is \[(7-\sqrt{73})/4\]
anonymous
  • anonymous
i am lost
anonymous
  • anonymous
is that what i put i in a calc
rob1525
  • rob1525
7 plus the square root of 73 then divide by 4...yes put that in ur calc
anonymous
  • anonymous
Its 19.25 ???? but that's not one of are answers
rob1525
  • rob1525
put in 7- square root(73) then divide that by 4 if u doo it right u will get the right answer.
anonymous
  • anonymous
-11.25 i do not know lol
rob1525
  • rob1525
what calc are u using?
anonymous
  • anonymous
Texas instruments Ti-30xa
rob1525
  • rob1525
okay good what is the square root of 73?
anonymous
  • anonymous
the square what does it look like
rob1525
  • rob1525
|dw:1378868212967:dw|
anonymous
  • anonymous
oh ok
rob1525
  • rob1525
that is the square root not square
rob1525
  • rob1525
square means|dw:1378868272900:dw|
anonymous
  • anonymous
its 5329
anonymous
  • anonymous
thats |dw:1378868405932:dw|
rob1525
  • rob1525
the square root of 73 looks like this|dw:1378868333883:dw| no its not 5329. u must be pressing the wrong botton. make sure u press the blue button before selecting the square root button.
anonymous
  • anonymous
my quare root is this |dw:1378868483251:dw|
anonymous
  • anonymous
8.544003745
rob1525
  • rob1525
YUP!!! now..
anonymous
  • anonymous
now what
rob1525
  • rob1525
7-8.544=?
anonymous
  • anonymous
-1.544
rob1525
  • rob1525
and now divide that by 4
anonymous
  • anonymous
-0.386
rob1525
  • rob1525
Bravo!!!!!!! ;D You found one of the x values.
anonymous
  • anonymous
yea
rob1525
  • rob1525
now do 7 + 8.544/4 to find the second x value but I think u can figure what the answer is by finding just one.. right?
anonymous
  • anonymous
or 3.886
anonymous
  • anonymous
its D right
rob1525
  • rob1525
there u go first add the two then divide 3.886 is the approximate answer....look again cuz its not d.
anonymous
  • anonymous
is it C
rob1525
  • rob1525
so u figures x = -.386 and the second one is x= 3.886 which ones are closest to those numbers...yes c. Good Job!
anonymous
  • anonymous
ok

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