1. Problem: Given $g(x) = \frac{x + 2}{5x - 1}$ with $x \neq \frac{1}{5}$, find the inverse function $g^{-1}(x)$ and determine if $g$ is one-one and onto.
2. To find the inverse, start by setting $y = g(x)$:
$$y = \frac{x + 2}{5x - 1}$$
3. Swap $x$ and $y$ to find the inverse function:
$$x = \frac{y + 2}{5y - 1}$$
4. Solve for $y$:
Multiply both sides by $(5y - 1)$:
$$x(5y - 1) = y + 2$$
$$5xy - x = y + 2$$
5. Rearrange terms to isolate $y$:
$$5xy - y = x + 2$$
$$y(5x - 1) = x + 2$$
6. Divide both sides by $(5x - 1)$:
$$y = \frac{x + 2}{5x - 1}$$
7. Notice this is the same as the original function, so the inverse is:
$$g^{-1}(x) = \frac{x + 2}{5x - 1}$$
8. Check if $g$ is one-one (injective):
Since $g$ is a rational function with a linear numerator and denominator and the denominator is not zero at $x=\frac{1}{5}$, it is strictly monotonic on intervals separated by $x=\frac{1}{5}$, so $g$ is one-one on its domain.
9. Check if $g$ is onto (surjective):
The function can take all real values except possibly the value that makes the denominator zero in the inverse, which is $x=\frac{1}{5}$. Hence, $g$ is onto its codomain excluding that point.
Final answer:
$$g^{-1}(x) = \frac{x + 2}{5x - 1}$$
"slug": "inverse g",
"subject": "algebra",
"desmos": {"latex": "y=\frac{x+2}{5x-1}","features": {"intercepts": true,"extrema": false}},
"q_count": 4
Inverse G E3B0A6
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.