If $8 - 3 (x + 2) = - 10$ and $7 (2 y - 3) = 3 + 8 y;$ find the value of $: 3 x^{2} - 4 x y - 5 y^{2} .$

- 66

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- 76

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- 86

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- 96

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Solution

The correct option is C $- 96$
$8 - 3 (x + 2) = - 10$
$8 - 3 x - 6 = - 10$
$x = 4$

$7 (2 y - 3) = 3 + 8 y$
$14 y - 21 = 3 + 8 y$
$6 y = 24$
$y = 4$
then the value of
$3 x^{2} - 4 x y - 5 y^{2} = 48 - 64 - 80 = - 96$

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Similar questions

3 - 3 (x + 2) = - 10

7 (2 y - 3) = 3 + 8 y

3 x^{2} - 4 x y + 5 y^{2}

In the given figure, $A O B$ is a straight line. If $∠ A O C = (3 x + 10)^{\circ}$ and $∠ B O C = (4 x - 26)^{\circ}$ , then $∠ B O C = ?$

(a) $96^{\circ}$

(b) $86^{\circ}$

(d) $106^{\circ}$ .

3 x - 2 y = 11

x y = 12

27 x^{3} - 8 y^{3}

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