Latihan Matematika Peminatan Kelas X Fungsi, Persamaan, dan Pertidaksamaan Eksponensial
# 9
Pilgan

Grafik fungsi f(x)=5(13)2xf\left(x\right)=5\left(\frac{1}{3}\right)^{2x} digeser ke kanan 1 satuan, lalu digeser ke bawah 3 satuan menghasilkan grafik fungsi h(x).h\left(x\right). Nilai h(2)h(0)h\left(-2\right)-h\left(0\right) adalah ....

A

3.600

B

3.400

C

3.200

D

3.000

E

3.800

Pembahasan:

Diketahui:

f(x)=5(13)2xf\left(x\right)=5\left(\frac{1}{3}\right)^{2x} digeser ke kanan 1 satuan, lalu digeser ke bawah 3 satuan menghasilkan grafik fungsi h(x).h\left(x\right).

Ditanya:

Nilai h(2)h(0)=?h\left(-2\right)-h\left(0\right)=?

Jawab:

Diketahui f(x)=5(13)2x.f\left(x\right)=5\left(\frac{1}{3}\right)^{2x}.

Ingat bahwa,

untuk a>0,a>0, grafik y=f(xa)y=f\left(x-a\right) artinya menggeser grafik y=f(x)y=f\left(x\right) sejauh aa ke arah kanan pada sumbu XX

untuk b>0b>0, grafik y=f(x)by=f\left(x\right)-b artinya menggeser grafik y=f(x)y=f\left(x\right) sejauh bb ke arah bawah pada sumbu YY.

Dari informasi yang diberikan, didapatkan bahwa h(x)=f(x1)3.h\left(x\right)=f\left(x-1\right)-3.

Dengan demikian,

h(2)h(0)=(f(21)3)(f(01)3)h\left(-2\right)-h\left(0\right)=\left(f\left(-2-1\right)-3\right)-\left(f\left(0-1\right)-3\right)

                         =f(3)3f(1)+3\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =f\left(-3\right)-3-f\left(-1\right)+3

                         =f(3)f(1)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =f\left(-3\right)-f\left(-1\right)

                         =5(13)2(3)5(13)2(1)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(\frac{1}{3}\right)^{2\left(-3\right)}-5\left(\frac{1}{3}\right)^{2\left(-1\right)}

                         =5(13)65(13)2\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(\frac{1}{3}\right)^{-6}-5\left(\frac{1}{3}\right)^{-2}

                         =5(1(13)6)5(1(13)2)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(\frac{1}{\left(\frac{1}{3}\right)^6}\right)-5\left(\frac{1}{\left(\frac{1}{3}\right)^2}\right)

                         =5(36)5(32)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(3^6\right)-5\left(3^2\right)

                         =572959\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\cdot729-5\cdot9

                         =5(7299)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(729-9\right)

                         =5(720)\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =5\left(720\right)

                         =3.600\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ =3.600

Jadi, nilai dari h(2)h(0)h\left(-2\right)-h\left(0\right) adalah 3.600.3.600.