If 2x+3y=12
xy=6
then find the value of 8x^3+27y^3
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hope my answer is correct
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twinkle56:
ok
nothing much
i sent 216x and 324y to right hand side
you are welcome
Answered by
4
since, 2x + 3y = 12
and, xy = 6
so,
8x³ + 27y³
= (2x)³ + (3y)³. (a³ + b³ = (a+b)(a²+ab+b²))
= (2x + 3y )[(2x)² + (2x)(3y) + (3y)²]
= 12 ( 4x² + 6xy + 9y²)
= 12 (4x² + 6 * 6 + 9y²)
= 12 (4x² + 36 + 9y²)
and, xy = 6
so,
8x³ + 27y³
= (2x)³ + (3y)³. (a³ + b³ = (a+b)(a²+ab+b²))
= (2x + 3y )[(2x)² + (2x)(3y) + (3y)²]
= 12 ( 4x² + 6xy + 9y²)
= 12 (4x² + 6 * 6 + 9y²)
= 12 (4x² + 36 + 9y²)
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