Question

if 2x+3y=8 and xy=2,find value of 8x^3+27y^3​

Answer 1

Answer:

476 is the answer.

Step-by-step explanation:

8x³+27y³

=(2x)³+(3y)³

=(2x+3y){(2x)²-2x×3y+(3y)²}

=(2x+3y)(4x²-6xy+9y²)

=(2x+3y){(2x)²+(3y)²}-6xy

=(2x+3y){(2x+3y)²-2×2x.3y}-6xy

=(2x+3y)(2x+3y)²-12xy-6xy

=(2x+3y)(2x+3y)²-18xy

=8×8²-18×2

=8×64-36

=512-36

=476