Question

当2x-y=5时,求-(2x-y)的二次方+3(2x-y)-二分之一(2x-y)+3(2x-y)的二次方的值.

Answer 1

因为 2x - y = 5

-(2x-y)^2 + 3(2x-y) - (1/2)(2x-y) + 3(2x-y)^2

= 2(2x - y)^2 + (5/2)(2x-y)

= 2×5^2 + (5/2)×5

= 50 + 25/2

= 125/2

= 62又(1/2)