Posted by
Aliah on
.
find the coefficient of x^5 in the expansion (x+2)(x+1)^8

MATH 
Damon,
x* (x+1)^8
+
2(x+1)^8
so
find coef of x^4 in (x+1)^8
find 2*coef of x^5 in (x+1)^*
add them

MATH 
Damon,
from binomial coefficient table
(x+1)^8 = x^8 ..... 56x^5+70x^4....+1
so 70 + 2(56) = 182

MATH 
Aliah,
182 is the final answer? Thank you for your help.