已知f(x+5)=5x2+1 求f(x)

问题描述:

已知f(x+5)=5x2+1 求f(x)

f(x+5)=5x^2+1
=5(x+5)^2-50x-125+1
=5(x+5)^2-50x-125-125+125+1
=5(x+5)^2-50x-250+126
=5(x+5)^2-50(x+5)+126
因为f(x+5)=5(x+5)^2-50(x+5)+126
所以f(x)=5x^2-50x+126