Question

If 3x+4y = 19&xy=-13 find the value of 9x square and 16y square

Answer 1

Solution:-

$9 {x}^{2} + 16 {y}^{2} = ({3x + 4y})^{2} - 24xy \\ = {19}^{2} + 24 \times 13 \\ 361 + 312 \\9 {x}^{2} + 16 {y}^{2} = 673$