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简化[f(x+h)－f(x)]/h,当1）f(x)=2x+3;2)f(x)=x²,要步骤急
题目详情
简化[f(x+h)－f(x)]/h,当 1）f(x)=2x+3 ; 2) f(x)=x² ,要步骤 急
▼优质解答
答案和解析
1.
f(x)=2x+3
=>f(x+h)=2(x+h)+3=2x+(2h+3)
[f(x+h)－f(x)]/h
=(2x+(2h+3)-2x-3)/h
=h
2.
f(x)=x^2
=>f(x+h)=(x+h)^2=x^2+2xh+h^2
[f(x+h)－f(x)]/h
=(x^2+2xh+h^2-x^2)/h
=2x+h
f(x)=2x+3
=>f(x+h)=2(x+h)+3=2x+(2h+3)
[f(x+h)－f(x)]/h
=(2x+(2h+3)-2x-3)/h
=h
2.
f(x)=x^2
=>f(x+h)=(x+h)^2=x^2+2xh+h^2
[f(x+h)－f(x)]/h
=(x^2+2xh+h^2-x^2)/h
=2x+h
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