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If $(2x + 3y)^2 = 4$ and $xy = -5$, what is the value of $4x^2 + 9y^2$?

Sagot :

Answer:

64

Step-by-step explanation:

(2x + 3y)^2 = 4

xy = -5

4x^2 + 9y^2

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(2x + 3y)^2 = 4                   [Start here]

4x^2 +12xy + 9y^2 = 4       [Expand]

4x^2 +12(-5) + 9y^2 = 4     [Substitute xy = -5]

4x^2 -60 + 9y^2 = 4            

4x^2 + 9y^2 = 4 + 60       [Rearrange]

4x^2 + 9y^2 = 64              [64 is the value of 4x^2 + 9y^2]