Question

$x ^{2} + y^{2} from 5x^{2} - 3y {?}^{2}$
Ans should be 4x^2-4y^2​

Answer 1

${x}^{2} + {y}^{2} from \: 5 {x}^{2} - 3 {y}^{2}$

=

$5 {x}^{2} - 3 {y}^{2} - ( {x}^{2} + {y}^{2} )$

=

$5 {x}^{2} - 3 {y}^{2} - {x}^{2} - {y}^{2}$

=

${x}^{2} (5 - 1) {y}^{2} ( - 3 - 1)$

=

${x}^{2} = 4 \: {y}^{2} = - 4$

=

$4 {x}^{2} - 4{y}^{2}$