if 5x - 4y = 12 and xy = -3 find the value of ( 5x + 4y ) ^2
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Answer:
-96
Step-by-step explanation:
5x-4y=12
squaring on both sides
25x^2+16y^2-40xy=144
25x^2+16y^2-40(-3)=144
25x^2+16y^2=144-120
25x^2+16y^2=24
Solve : (5x+4y)^2
=25x^2+16y^2+40xy
=24+40(-3)
=24-120
=-96
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