Jawabanmu

2013-12-28T15:37:28+07:00
2x+1=a
x=(a-1)/2
substitusikan x ke persamaan dapet a^2-a-5
f(a)=a^2-a-5
f(2)=4-2-5=-3
2013-12-28T21:32:54+07:00
Karena di soal bukan f(x) tpi f(2x+1)
kita cari dlu nilai x nya
f(2x+1)=f(2)\\
2x+1=2\\
2x=2-1\\
x= \frac{1}{2}\\\\

f(2)=4x^2+2x-5\\
f(2)=4(\frac{1}{2})^2+2(\frac{1}{2})-5\\
f(2)=4(\frac{1}{4})+1-5\\
f(2)=1+1-5\\
f(2)= -3