把下列二次函数配方f(x)=3+5x-2x²

问题描述:

把下列二次函数配方f(x)=3+5x-2x²
f(x)=3+5x-2x²
f(x)=四分之三x&sup2-2x

f(x)=-2x²+5x+3=-2(x²-5x/2)+3=-2(x²-5x/2+25/16-25/16)+3=-2(x²-5x/2+25/16)+2×25/16+3=-2(x-5/4)²+49/8f(x)=3/4*x²-2x=(3/4)(x²-8x/3)=(3/4)(x²-8x/3+16/9-16/9)=(3/4)(...