f(x)=5x^2-4x-3f(x)=-3x^2+5x-8配方

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f(x)=5x^2-4x-3f(x)=-3x^2+5x-8配方

f(x)=5x^2-4x-3

f(x)=-3x^2+5x-8
配方

f(x)=5x^2-4x-3f(x)=-3x^2+5x-8配方
f(x)=5x²-4x-3=5(x²-4x/5)-3=5[(x-2/5)²-4/25]-3=5(x-2/5)²-4/5-3=5(x-2/5)²-19/5
f(x)=-3x²+5x-8=-3(x²-5x/3)-8=-3[(x-5/6)²-25/36]-8=-3(x-5/6)²+25/12-8=-3(x-5/6)²-71/12.

解:
f(x)=5x^2-4x-3
=5(x^2-4/5x+(4/10)^2-(4/10)^2)-3
=5(x-4/10)^2-5(4/10)^2 -3
f(x)=-3x^2+5x-8
=-3(x^2-5/3x+(5/6)^2-(5/6)^2) -8
=-3(x-5/6)^2 +3(5/6)^2 -8

5(x-2/5)^2-19/5
-3(X-5/6)^2-71/12

f(x)=5x^2-4x-3
= 5(x²-(4/5)x+4/25)-3-4/5
= 5(x-2/5)²-19/5
f(x)=-3x^2+5x-8
= -3(x²-(5/3)x+(25/36))-8+25/12
= -3(x-5/6)²-71/12