Question

a + b = 9 and ab = 20, find the value of (a² + b²).​

Answer 1

$(a + b)^{2} = a ^{2} + b ^{2} + 2ab$

$a ^{2} + b ^{2} = (a + b) ^{2} - 2ab$

=81-2(20)

=81-40

=41