Answer:
[tex]f(x) = {3}^{x} \\ f(x +1) = {3}^{(x + 1)} \\ f(x) + f(x + 1) \\ = {3}^{x} + {3}^{(x + 1)} \\ = {(1 \times 3}^{x} ) +( 3 \times {3}^{x} ) \\ By \: taking \: {3}^{x} \: common, \: we \: get \\ (1 + 3) \times {3}^{x} \\ = 4 \times {3}^{x} \\ = 4f(x)[/tex]
- f(x)+f(x+1)=4f(x), when f(x)=3^x
- Hence proved
