If 2x+3y=8 and xy=4 find 4x^2+9y^2
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Step-by-step explanation:
2x+3y=8
By squaring both sides.
(2x+3y)^2=8^2
By using identity : (a+b) ^2=a^2+b^2+2ab
4x^2+9y^2+12xy =64
4x^2+9y^2+12(4)=64
4x^2+9y^2+48=64
4x^2+9y^2=64-48
4x^2+9y^2=16
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