Which set of steps shows how to find f(-2) when f(x) = -2x – 3?
Understand the Problem
The question asks which steps are correct to evaluate the function f(x) = -2x - 3 at x = -2. This involves substituting -2 for x in the given expression and simplifying.
Answer
$f(-2) = 1$
Answer for screen readers
$f(-2) = 1$
Steps to Solve
- Substitute -2 for x in the function
Replace every instance of $x$ in the function $f(x) = -2x - 3$ with $-2$.
$$ f(-2) = -2(-2) - 3 $$
- Multiply -2 by -2
Multiply $-2$ by $-2$, which gives positive $4$.
$$ f(-2) = 4 - 3 $$
- Subtract 3 from 4
Subtract $3$ from $4$.
$$ f(-2) = 1 $$
$f(-2) = 1$
More Information
The function $f(x) = -2x - 3$ is a linear function. Evaluating a function at a specific point means finding the $y$-value of the function for a given $x$-value. In this case, when $x = -2$, $y = 1$.
Tips
A common mistake is to incorrectly apply the negative sign when multiplying. For example, $-2 \times -2$ is often incorrectly calculated as $-4$. Another common mistake is to perform the operations in the wrong order. Remember to perform multiplication before addition or subtraction.
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