Question

Se a+b = 10 e ab = 4, calcule a²+b².

Answer 1

a+b= 10

(a+b)²= 10²

a²+ab+ab+b²= 100

a²+2ab+b²= 100

a²+b²= 100-2ab

a²+b²= 100-2(4)

a²+b²= 100-8

a²+b²= 92

Resposta → a²+b²= 92

Answer 2

a  + b = 10

ab = 4

elevando ao quadrado  

( a + b)² = 10²

[ (a)²  + 2 * a * b + (b)² ] = 100

a² + 2ab + b² = 100

a² + b²  + 2ab  = 100

substituindo ab por 4

( a² + b² ) + 2 * 4 = 100

( a² + b² ) + 8 = 100

( a² + b² ) = 100 - 8

a² + b² = 92 *****  resposta