- #1
naffle
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Homework Statement
When rx^3 + gx^2 +4x + 1 is divided by x-1, the remainder is 12. When it is divided by x+3, the remainder is -20. Find the values of r and g.
Homework Equations
The Attempt at a Solution
r=f(1)
=r(1)^3 + g(1)^2 + 4(1) +5
=r + g +9
r=12
r+g+9=12
r+g= 3
r=f(-3)
=r(-3)^3 + g(-3)^2 + 4(-3) +5
=-27r +9g -7
r=-20
-27r +9g -7=-20
-27 +9g=-13
Then I was just going to use elimination to find r and g.
-27r-27g=-81 (equation 1 multiplied by -27)
-27r+9g=-13
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-36g=-68
g= 1.89
But that answer is wrong.
Is one of my equations wrong or am I going about it incorrectly?
I was able to find the unknown in a equation similar to this, so I'm not sure why I'm having such trouble with this one.
Thanks for any help!