Timmy writes the equation $f(x)=\frac{1}{4} x-1$. He then doubles both of the terms on the right side to create the equation $g(x)=\frac{1}{2} x-2$. How does the graph of $g(x)$ compare to the graph of $f(x)$?


AThe line of $g(x)$ is steeper and has a higher $y$-intercept.
BThe line of $g(x)$ is less steep and has a lower $y$-intercept.
CThe line of $g(x)$ is steeper and has a lower $y$-intercept.
DThe line of $g(x)$ is less steep and has a higher $y$-intercept.

Verified Answer :

  • Identify the slope \(m\) and y-intercept \(b\) for both functions: \(f(x) = \frac{1}{4}x - 1\) and \(g(x) = \frac{1}{2}x - 2\).
  • Compare the absolute values of the slopes: \(|0.5| > |0.25|\), confirming that \(g(x)\) is steeper.
  • Compare the y-intercepts: \(-2 < -1\), confirming that the y-intercept of \(g(x)\) is lower.
  • The graph of \(g(x)\) is steeper and has a lower \(y\)-intercept. \(\boxed{\text{The line of } g(x) \text{ is steeper and has a lower } y\text{-intercept.}}\)

Explanation

  1. Analyzing the linear functions

The function \(f(x) = \frac{1}{4}x - 1\) represents a line in the coordinate plane. Comparing it to the standard form of a linear equation \(y = mx + b\), where \(m\) is the slope and \(b\) is the y-intercept, we can see that for \(f(x)\), the slope \(m_f = \frac{1}{4}\) and the y-intercept \(b_f = -1\). The new function \(g(x) = \frac{1}{2}x - 2\) also follows this form, with a slope \(m_g = \frac{1}{2}\) and a y-intercept \(b_g = -2\).

  1. Comparing steepness

The steepness of a line is determined by the absolute value of its slope \(|m|\). Comparing the slopes of the two functions:

  • For \(f(x)\), \(|m_f| = |\frac{1}{4}| = 0.25\).
  • For \(g(x)\), \(|m_g| = |\frac{1}{2}| = 0.5\).

Since \(0.5 > 0.25\), the absolute value of the slope for \(g(x)\) is greater than that for \(f(x)\), which means the graph of \(g(x)\) is steeper than the graph of \(f(x)\).

  1. Comparing y-intercepts

The y-intercept represents the point where the line crosses the y-axis, given by the value of \(b\) when \(x = 0\).

  • For \(f(x)\), the y-intercept is \(-1\).
  • For \(g(x)\), the y-intercept is \(-2\).

Since \(-2 < -1\), the y-intercept of \(g(x)\) is lower than the y-intercept of \(f(x)\).

  1. Conclusion

Based on the analysis of the slopes and y-intercepts, the graph of \(g(x)\) is steeper than the graph of \(f(x)\) and has a lower y-intercept. Thus, the correct description is that the line of \(g(x)\) is steeper and has a lower \(y\)-intercept.

Examples

Consider road construction where you are designing an incline or a ramp. The steepness of the ramp is modeled by the slope of a line. If you change the design of a ramp from a slope of \(\frac{1}{4}\) (for every 4 meters of horizontal distance, the ramp rises 1 meter) to a slope of \(\frac{1}{2}\) (for every 2 meters of horizontal distance, the ramp rises 1 meter), the ramp becomes significantly steeper and harder to climb. Similarly, the y-intercept represents the starting height of the ramp. A lower y-intercept means the ramp starts from a deeper point in the ground or a lower platform. Understanding these changes helps engineers and designers accurately modify structures for accessibility or safety.