Question

if 2x + 3y= 10 and xy = 10 then what is 4x^2 +9y^2

Answer 1

Answer:

-20

Step-by-step explanation:

2x + 3y = 10

( 2x + 3y)^2 = 10^2

4x^2 + 12xy + 9y^2 = 100

4x^2 + 12*10 + 9y^2 = 100

4x^2 +9y^2 = 100 - 120 = -20

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Answer 2

$2x + 3y = 10 \: \: \: \: and \: \: xy = 10 \\ \\ = > 4 {x}^{2} + 9 {y}^{2} = ( {2x)}^{2} + ( {3y)}^{2} \\ \\ = ( {2x + 3y)}^{2} - 2.2x.3y \\ \\ = ( {2x + 3y)}^{2} - 12xy \\ \\ = ( {10)}^{2} - 12 \times 10 \\ \\ = 100 - 120 \\ \\ = - 20$

I hope this helps you.