SOLUTION: Transform the expression below into normal form. For what values of b is the coefficient of x equal to zero? (x^2+2x+b) (x^2+2x-5)

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Transform the expression below into normal form. For what values of b is the coefficient of x equal to zero? (x^2+2x+b) (x^2+2x-5)      Log On


   

Question 1177557: Transform the expression below into normal form. For what values of b is
the coefficient of x equal to zero?
(x^2+2x+b) (x^2+2x-5)
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
%28x%5E2%2B2x%2Bb%29+%28x%5E2%2B2x-5%29...multiply
x%5E4%2B2x%5E3-5x%5E2%2B2x%5E3%2B4x%5E2-10x%2Bbx%5E2%2B2bx-5b....rearrange
x%5E4+%2B+4+x%5E3+%2Bbx%5E2+-+x%5E2%2B+2bx+-+10x-+5b.....group terms with x
x%5E4+%2B+4+x%5E3+%2Bbx%5E2+-+x%5E2%2B+2x%28b+-+5%29-+5b

the coefficient of x will be only equal to zero if b=5
check:
%28x%5E2%2B2x%2B5%29+%28x%5E2%2B2x-5%29=x%5E4+%2B+4x%5E3+%2B+4+x%5E2+-+25