Question

factor .note the middle term has already been split
u^2+2u+8u+16

Answer 1

u=13 0r -23

Answer 2

u^(2)+2u+8u+16

Since 2u and 8u are like terms, add 8u to 2u to get 10u.
u^(2)+10u+16

Since the coefficient of u^(2) is 1, the coefficients of the left-hand term in each factor must be 1.
(u )(u )

For a polynomial of the form ax^(2)+bx+c, find two factors of c (16) that add up to b (10).
a=1, b=10, c=16

In this problem 8*2=16 and 8+2=10, so insert 8 as the right hand term of one factor and 2 as the right-hand term of the other factor.
(u+8)(u+2)