Question

Find X square + Y square if X + Y is equal to - 14 and x * Y is equal to 84

Answer 1

Given that
$x + y = 14$
and
$x \times y = 84$
we know that
$(x + y) {2} = x {2} + y {2} + 2xy$
$(14) {2} = x {2} + y {2} + (2 \times 84)$
$x {2} + y {2} = 28$