Q. Find the x-intercept of the Line \( 3x + 20y = -24 \)
Answer
- Set y to 0.\[ 3x + 20(0) = -24 \]
- Solve for x.\[ 3x = -24 \]
\[ x = -8 \]
- State the x-intercept.\[ (-8, 0) \]
Detailed Explanation
Step-by-step solution
- Understand what an x-intercept is.
The x-intercept is the point where the graph crosses the x-axis, so the y-coordinate there equals 0. In other words, set \(y = 0\). - Substitute \(y = 0\) into the equation.
Start with the given line: \(3x + 20y = -24\).
Replacing \(y\) with \(0\) gives \(3x + 20(0) = -24\). - Simplify the equation.
Compute \(20(0) = 0\), so the equation becomes \(3x = -24\). - Solve for \(x\).
Divide both sides of \(3x = -24\) by \(3\) to isolate \(x\). This uses the property that if \(a = b\) then \(\dfrac{a}{3} = \dfrac{b}{3}\).
Thus \(x = \dfrac{-24}{3} = -8\). - State the x-intercept as a point.
The x-intercept is the point \((-8, 0)\).
Final answer: The x-intercept is \((-8, 0)\).
Graph
Frequently Asked Questions
What is an x-intercept?
The x-intercept is the point where graph crosses the x-axis; its y-coordinate is 0.
How do I find the x-intercept of 3x + 20y = -24?
Set y = 0: 3x = -24, so x = -8. The x-intercept is (-8, 0).
How do I find the y-intercept of the same line?
Set x = 0: 20y = -24, so y = -24/20 = -6/5. The y-intercept is (0, -6/5).
How can I convert the equation to slope-intercept form?
Solve for y: 20y = -3x - 24, so y = (-3/20)x - 6/5.
What is the slope and what does it tell me?
The slope is -3/20; it means the line falls 3 units for every 20 units it moves right.
How can I graph this line using intercepts?
Plot (-8, 0) and (0, -6/5), then draw the straight line through those two points.
How do I check my x-intercept is correct?
Substitute (-8, 0) into the original equation: 3(-8) + 20(0) = -24, which is true.
What if the coefficient of x were zero—would there be an x-intercept?
If the x-coefficient is 0, the equation is horizontal (y = constant). It has an x-intercept only if that constant is 0; otherwise no x-intercept.
Can x-intercepts be fractions or decimals?
Yes. Depending on coefficients and constants, x-intercepts can be integers, fractions, or decimals.
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