Question

If 3x + 2y=12
xy=6
Find the value of 9x square + 4x square

Answer 1

Answer:

72

Step-by-step explanation:

$9 {x}^{2} + 4 {y}^{2} \\ = {(3x)}^{2} + {(2y)}^{2} \\ = {(3x + 2y)}^{2} - 2 \times 3x \times 2y \\ = {(12)}^{2} - 12 \times xy \: \: \: \: \: (given \: 3x + 2y = 12) \\ = 144 - 12 \times 6 \: \: \: \: \: (given \: xy = 6) \\ = 144 - 72 \\ = 72$

Answer 2

Answer:

9x sq. + 4x sq. = 72

Step-by-step explanation:

3x + 2y = 12

(3x + 2y) ^2 = (12)^2

9x^2 + 12xy + 4y^2 = 144

9x^2 + 12(6) + 4y^2 = 144

9x^2 + 72 + 4y^2 = 144

9x^2 +4y^2 = 144 - 72

9x^2 + 4y^2 = 72