Question

Which expression is a factor of 21x2 + 13x – 20?A. 3x – 4B. 7x - 5C. 7x + 4D. 3x + 5

Answer 1

Answer:

B. 7x - 5

Explanation

Given the expression 21x^2 + 13x – 20, to get which of the given expression is a factor we will have to factorize the equation first as shown;

21x^2 + 13x – 20

= 21x^2 + 28x - 15x - 20

= 7x(3x+4) -5(3x+4)

= (7x-5)(3x+4)

Hence one of the factors is 7x - 5