Question

Select one of the factors of 5x^2 + 7x + 2.

A) (5x − 2)
B) (x + 2)
C) (5x + 1)
D) None of the above

Answer 1

Correct choice is D

Explanation:

Consider the quadratic expression
`5x^2 + 7x + 2.`

First, find the discriminant:

`D=7^2-4\cdot 5\cdot 2=49-40=9.`

Now find the roots of the quadratic expression
`5x^2 + 7x + 2:`

`x_(1,2)=(-7\pm √(9))/(2\cdot 5)=(-7\pm 3)/(10)=-1,\ -0.4.`

Then

`5x^2 + 7x + 2=5(x-(-1))(x-(-0.4))=5(x+1)(x+0.4)=(x+1)(5x+2).`