Q. Find the x-intercept of the Line \( 3x + 20y = -24 \)

Answer

  1. Set y to 0.\[ 3x + 20(0) = -24 \]
  2. Solve for x.\[ 3x = -24 \]

    \[ x = -8 \]

  3. State the x-intercept.\[ (-8, 0) \]

Detailed Explanation

Step-by-step solution

  1. 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 \(y = 0\).
  2. Substitute \(y = 0\) into the equation.
    Start with the given line: \(3x + 20y = -24\).
    Replacing \(y\) with \(0\) gives \(3x + 20(0) = -24\).
  3. Simplify the equation.
    Compute \(20(0) = 0\), so the equation becomes \(3x = -24\).
  4. 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 \(x = \dfrac{-24}{3} = -8\).
  5. State the x-intercept as a point.
    The x-intercept is the point \((-8, 0)\).

Final answer: The x-intercept is \((-8, 0)\).

Graph

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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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