SOLUTION: let {{{f(x) = 2x^3 - 7x +2}}} A) calculate f(0), f(1), f(2), f(-1), and f(-2). which of these is useful in factorizing f? B) from the previous part, you have a factor x - a of f(

Algebra ->  Equations -> SOLUTION: let {{{f(x) = 2x^3 - 7x +2}}} A) calculate f(0), f(1), f(2), f(-1), and f(-2). which of these is useful in factorizing f? B) from the previous part, you have a factor x - a of f(      Log On


   



Question 1036514: let f%28x%29+=+2x%5E3+-+7x+%2B2
A) calculate f(0), f(1), f(2), f(-1), and f(-2). which of these is useful in factorizing f?
B) from the previous part, you have a factor x - a of f(x) for some a. then you can write 2x%5E3+-+7x+%2B2+=+%28x-a%29Multiply%28Ax%5E2+%2B+Bx+=+C%29
for some choice of numbers A, B, and C. two of the numbers can be determined by inspection - that is, by looking. which two?
C)by considering the x^2 term (or the x term) on the right hand side, and match with the corresponding piece on the left hand side, compute the remaining number of A, B, and C that you have not yet determined.
D) solve f(x) = 0
E) sketch y=+2x%5E3+-+7x+%2B2
F) use your sketch to solve 2x%5E3+-+7x+%2B2%3C0

Answer by robertb(5830) About Me  (Show Source):
You can put this solution on YOUR website!
A) f(0) = 2, f(1) = -3, f(2) = 4, f(-1) = 7, and f(-2) = 0, all determined by direct substitution.
B) 2x%5E3+-+7x+%2B2+=+%28x-a%29%2A%28Ax%5E2+%2B+Bx+%2BC%29.
From part (A), we find that -2 is a zero of f(x), and so x + 2 is a factor of f(x).
==> 2x%5E3+-+7x+%2B2+=+%28x%2B2%29%2A%28Ax%5E2+%2B+Bx+%2BC%29.
Also, it is quite easy to see that A = 2, and the constant C has to be C = 1.
==> 2x%5E3+-+7x+%2B2+=+%28x%2B2%29%2A%282x%5E2+%2B+Bx+%2B1%29.
C) Expanding the right-hand side but considering only the coefficient of 0 of x%5E2, we get %28B%2B4%29x%5E2+=+0.
==> B = -4.
D) Thus 2x%5E3+-+7x+%2B2+=+%28x%2B2%29%2A%282x%5E2+-4x+%2B1%29. The other two zeros are x+=+%282+%2B-+sqrt%282+%29%29%2F2+.
E) graph%28+300%2C+200%2C+-5%2C+5%2C+-5%2C+5%2C+2x%5E3+-+7x+%2B2%29
F) This is easy and so I leave this up to you. (Look at the parts of the graph that are below the x-axis.)