# How do you factor the expression  8x^2+ 38x + 9?

May 2, 2017

$8 {x}^{2} + 38 x + 9$

Find two numbers that multiply to $9 \cdot 8 = 72$ and add to $38$:
The two numbers are $2 \mathmr{and} 36$:

$= 8 {x}^{2} + 2 x + 36 x + 9$

$= 2 x \left(4 x + 1\right) + 9 \left(4 x + 1\right)$

$= \left(2 x + 9\right) \left(4 x + 1\right)$