Q. Find the x-intercept of the Line \( 5x + 18y = 4 \)
Answer
- Set y to 0.
Substituting y = 0 leaves us with the x terms.
\[ 5x = 4 \]
- Solve for x.
Divide by 5.
\[ x = \frac{4}{5} \]
- State the x-intercept.
\[ \left(\frac{4}{5}, 0\right) \]
Detailed Explanation
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Step 1 — Recall what an x-intercept is.
The x-intercept is the point where the graph crosses the x-axis, so the y-coordinate is 0. To find the x-intercept of the line, set \(y = 0\) in the equation and solve for \(x\).
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Step 2 — Substitute \(y = 0\) into the equation.
Start with the line equation: \(5x + 18y = 4\). Substitute \(y = 0\) to get \(5x + 18(0) = 4\).
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Step 3 — Simplify the equation.
Since \(18(0) = 0\), the equation becomes \(5x = 4\).
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Step 4 — Solve for \(x\).
Divide both sides by 5 to isolate \(x\): \(x = \frac{4}{5}\). In decimal form, \(x = 0.8\).
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Step 5 — State the x-intercept as an ordered pair.
The x-intercept is \(\left(\frac{4}{5},\,0\right)\), which is the same as \((0.8,\,0)\).
Graph
Frequently Asked Questions
What is the x-intercept of 5x + 18y = 4?
Set y = 0: 5x = 4, so x = 4/5. The x-intercept is (4/5, 0) or (0.8, 0).
How do you find the x-intercept of line given in standard form ax + by = c?
Set y = 0, solve ax = c, so x = c/(provided ≠ 0). The intercept is (c/a, 0).
How do you find the x-intercept from slope-intercept form y = mx + b?
Set y = 0 and solve 0 = mx + b, so x = -b/m, assuming m ≠ 0. The x-intercept is (-b/m, 0).
What if = 0 in ax + by = c — does the line have an x-intercept?
If = 0 the equation is by = c. If c ≠ 0 there is no x-intercept; if c = 0 the line is y = 0, which is the x-axis (every point is an x-intercept).
How do you find the y-intercept of 5x + 18y = 4?
Set x = 0: 18y = 4, so y = 4/18 = 2/9. The y-intercept is (0, 2/9).
How can intercepts help you graph line quickly?
Plot the x- and y-intercepts as points on the axes, then draw straight line through them. Two intercepts uniquely determine the line.
How do you check your x-intercept calculation?
Substitute the x value into the original equation with y = 0 to verify the equation holds. For 5x + 18(0) = 4, 5(4/5) = 4, so it checks.
Should I convert fractions to decimals for the x-intercept?
Either form is fine. Use fractions for exact values (4/5), decimals for readability (0.8). Keep fractions when doing algebrto avoid rounding errors.
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Math, Calculus, Geometry, etc.
Math, Calculus, Geometry, etc.