Question

X²+y²=18,xy=6 find the value of (2x/3-2y/3)²

Just use any of the following identity to solve this

a²+2ab+b²

a²-2ab+b²

(a-b)(a+b)

Answer 1

Explanation:

2x+3y=12 xy=6

8x

3

+27y

3

=(2x)

3

+(3y)

3

=a

3

+b

3

=(a+b)(a

2

+b

2

−ab)

8x

3

+27y

3

=(2x+3y)((2x)

2

+(3y)

2

−(2x)(3y))

=(12)[(2+3y)

2

−12xy−6xy]

=(12)[(12)

2

−18(6)]

=12[144−108]

=12×36

=432.