Question

11. Let f(x) = 2x² + 7x + 5

Answer 1

Answer:

(x+1)(2x+5)

Step-by-step explanation:

f(x) = 2x² + 7x + 5

Factor the expression by grouping. First, the expression needs to be rewritten as 2x²+ax+bx+5. To find a and b, set up a system to be solved.

a+b=7

ab=2×5=10

Since ab is positive, a and b have the same sign. Since a+b is positive, a and b are both positive. List all such integer pairs that give product 10.

1,10

2,5

Calculate the sum for each pair.

1+10=11

2+5=7

The solution is the pair that gives sum 7.

a=2

b=5

2x²+7x+5 as (2x²+2x)+(5x+5).

(2x²+2x)+(5x+5)

Factor out 2x in the first and 5 in the second group.

2x(x+1)+5(x+1)

Factor out common term x+1 by using distributive property.

(x+1)(2x+5)