Answer:
[tex]f(-4) = 64[/tex]
Step-by-step explanation:
Given
[tex](x_1,y_1) = (1,2)[/tex]
[tex](x_2,y_2) = (2,1)[/tex]
Required
Find f(-4)
We have that:
[tex]y = ab^x[/tex]
For [tex](x_1,y_1) = (1,2)[/tex]
[tex]2 = ab^1[/tex]
[tex]2 = ab[/tex]
For [tex](x_2,y_2) = (2,1)[/tex]
[tex]1 = ab^2[/tex]
Rewrite as:
[tex]1 = ab * b[/tex]
Make b the subject
[tex]b = \frac{1}{ab}[/tex]
Substitute: [tex]2 = ab[/tex]
[tex]b = \frac{1}{2}[/tex]
Substitute [tex]b = \frac{1}{2}[/tex] in [tex]2 = ab[/tex]
[tex]2 = a * \frac{1}{2}[/tex]
[tex]a = 2 * 2[/tex]
[tex]a = 4[/tex]
To calculate f(-4), we have:
[tex]f(x) = ab^x[/tex]
[tex]f(-4) = 4 * \frac{1}{2}^{(-4)}[/tex]
[tex]f(-4) = 4 * 16[/tex]
[tex]f(-4) = 64[/tex]
