f(x)=x2+3x−4
f(x+2)−f(2)=(x+2)2+3×(x+2)−4−22+3×2−4
f(x+2)−f(2)=x2+2x+2x+4+3×(x+2)−4−22+3×2−4
f(x+2)−f(2)=x2+4x+4+3×(x+2)−4−22+3×2−4
f(x+2)−f(2)=x2+4x+4+3x+6−4−4+3×2−4
f(x+2)−f(2)=x2+4x+4+3x+6−4−4+6−4
f(x+2)−f(2)=x2+7x+4+6−4−4+6−4
f(x+2)−f(2)=x2+7x+10−4−4+6−4
f(x+2)−f(2)=x2+7x+6−4+6−4
f(x+2)−f(2)=x2+7x+2+6−4
f(x+2)−f(2)=x2+7x+8−4
f(x+2)−f(2)=x2+7x+4
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