An exponential function [tex]$f(x)=ab^x$[/tex] passes through the points [tex]$(0, 7000)$[/tex] and [tex][tex]$(2, 1120)$[/tex][/tex]. What are the values of [tex]a[/tex] and [tex]b[/tex]?

[tex]\[
\begin{array}{l}
a = \square \\
b = \square
\end{array}
\][/tex]



Answer :

To determine the values of [tex]\(a\)[/tex] and [tex]\(b\)[/tex] for the exponential function [tex]\(f(x) = ab^x\)[/tex] that passes through points [tex]\((0, 7000)\)[/tex] and [tex]\((2, 1120)\)[/tex], we can follow these steps:

1. Point (0, 7000):
When [tex]\(x = 0\)[/tex]:
[tex]\[ f(0) = ab^0 = a \cdot 1 = a \][/tex]
Since [tex]\(f(0) = 7000\)[/tex], we have:
[tex]\[ a = 7000 \][/tex]

2. Point (2, 1120):
When [tex]\(x = 2\)[/tex]:
[tex]\[ f(2) = ab^2 \][/tex]
Given [tex]\(f(2) = 1120\)[/tex], we substitute [tex]\(a\)[/tex] from the first point:
[tex]\[ 1120 = 7000 \cdot b^2 \][/tex]

3. Solve for [tex]\(b^2\)[/tex]:
We need to isolate [tex]\(b^2\)[/tex]. Divide both sides by 7000:
[tex]\[ b^2 = \frac{1120}{7000} \][/tex]

4. Simplify the fraction:
[tex]\[ b^2 = \frac{112}{700} = \frac{16}{100} = 0.16 \][/tex]

5. Solve for [tex]\(b\)[/tex]:
Take the square root of both sides to find [tex]\(b\)[/tex]:
[tex]\[ b = \sqrt{0.16} = 0.4 \][/tex]

Putting all this together, the values are:
[tex]\[ \begin{array}{l} a = 7000 \\ b = 0.4 \end{array} \][/tex]