Question

已知(2x-y)²=9,求+8x²-8xy+2y²-8x+4y-6的值？

Answer 1

(2x-y)²=9
8x²-8xy+2y²-8x+4y-6
=2(2x-y)²-4(2x-y)-6
=2×9-4×(±3)-6
=12±12
=0或=24

Answer 2

(2x-y)^2=9
2x-y = 3 or -3
//
8x^2-8xy+2y^2-8x+4y-6
=2(2x-y)^2 -8x+4y-6
=2(2x-y)^2 -4(2x-y)-6
=18-4(2x-y)-6
=12-4(2x-y)
=12-4(-3) or 12-4(3)
=24 or 0