9x^2+38xy+8y^2

Question

Writing the expression in factored form. 

Answer 1

9x^2+38xy+8y^2

= (9x+2y)(x+4y)

Answer 2

Alecia, you just look at the factors of 9 and 8 in which the combination will add to 38.

 

The factors of  9 are 1 by 9 and 3 by 3

 

And 8 is 1 by 8 and 2 by 4

 

Looks like the factors that would work is 9 by 1 and 2 by 4 Hence,

 

9x^2+38xy+8y^2 = (9x+2y)(x+4y) = 9x^2+36xy+2xy+8y^2 = 9x^2+38xy+8y^2

 

Hence, this combination works using the foil method.