Question

(1)求函数y=2的x+1次方-1,(x大于等于0的反函数);(2)求函数y=2log底数3真数(x方+2x+4)的值域

Answer 1

y=2^(x+1)-1,x>=0,则有y>=2-1=12^(x+1)=y+1x+1=log2(y+1)x=log2(y+1)-1即反函数是y=log2(x+1)-1,(x>=1)(2)y=2log3(x^2+2x+4)x^2+2x+4=(x+1)^2+3>=3故有y>=2log3(3)=2即值域是[2,+无穷)