Question

sabendo que a+b=13 , quanto vale a²+2ab+b² ?

Answer 1

$a + b = 13 \\ \\ (a + b)^2 = 13^2 \\ \\ \boxed{a^2 + 2ab + b^2 = 169}$

Answer 2

 a + b = 13a²+2ab+b² = (a + b)² 
(a + b)² = ( 13 )² = 169