化简并求值x^2-1/2【x-1/2（x^2+x）】 x=2 求值_数学解答

化简并求值
x^2-1/2【x-1/2（x^2+x）】 x=2 求值

人气：171 ℃　时间：2020-02-06 01:29:53

解答

=x²-1/2(x-1/2x²+1/2x)
=x²-1/2(3/2x-1/2x²)
=x²-3/4x+1/4x²
=5/4x²-3/4x
=5/4*2²-3/4*2=7/2