Question 30341: Which of the following is a factor of the polynomial x^2 - x - 20?
A) x-5
B) x-4
C) x+2
D) x+5
E) x+10 Found 2 solutions by sdmmadam@yahoo.com, venugopalramana:Answer by sdmmadam@yahoo.com(530) (Show Source):
You can put this solution on YOUR website! x^2 - x - 20 ----(1)
=x^2 - 5x+4x - 20 (splitting the middle term (-x) into two terms so that their sum is (-x) and their product is the product of the square term and the constant term.)
=(x^2 - 5x)+ (4x - 20)
=x(x-5)+4(x-5)
=xp+4p where p= (x-5)
= p(x+4)
=(x-5)(x+4)
This means (x-5) and (x+4) are factors
Of the given choices, the choice A) holds
You can put this solution on YOUR website! Which of the following is a factor of the polynomial x^2 - x - 20?
THERE ARE 2 METHODS
1 FACTORISE AND CHECK..F(X)=X^2-X-20=X^2-5X+4X-20=X(X-5)+4(X-5)=(X-5)(X+4)
SO...A...X-5 IS THE ANSWER.
2...PUT X=5,4,-2..ETC..AS PER THE ANSWERS AND CHECK WHEN FUNCTION F(X) BECOMES ZERO..WE SEE THAT F(5)=0..SO X-5 IS A FACTOR.
A) x-5
B) x-4
C) x+2
D) x+5
E) x+10
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