Q. Find the x-intercept of the line \(y=18x+6\).
Answer
Set y to 0: \(0=18x+6\). Solve: \(18x=-6\), \(x=-\frac{6}{18}=-\frac{1}{3}\).
x-intercept: \(\left(-\frac{1}{3},0\right)\)
Detailed Explanation
Find the x-intercept of the line
We are given the equation of the line
\( y = 18x + 6 \)
- Understand what the x-intercept means.The x-intercept is the point where the graph crosses the x-axis. At that point, the y-coordinate equals 0. Therefore to find the x-intercept, set y equal to 0 in the equation and solve for x.
- Set y to 0 and write the equation to solve.\( 0 = 18x + 6 \)
- Isolate the term containing x.Subtract 6 from both sides to move the constant term:
\( 0 – 6 = 18x + 6 – 6 \)
which simplifies to
\( -6 = 18x \)
- Solve for x by dividing both sides by 18.\( x = \dfrac{-6}{18} \)
- Simplify the fraction.Both numerator and denominator have a common factor of 6, so divide top and bottom by 6:
\( x = \dfrac{-6 \div 6}{18 \div 6} = \dfrac{-1}{3} \)
- State the x-intercept as a point and verify.The x-intercept is the point \( \left(-\tfrac{1}{3},\,0\right) \).
Verification: substitute \( x = -\tfrac{1}{3} \) into the original equation:
\( y = 18\left(-\tfrac{1}{3}\right) + 6 = -6 + 6 = 0 \), which confirms the result.
See full solution
Algebra FAQs
How do you find the x-intercept of the line \(y=18x+6\)?
Set \(y=0\) and solve: \(0=18x+6\) gives \(x=-\tfrac{6}{18}=-\tfrac{1}{3}\). The x-intercept is \(\left(-\tfrac{1}{3},0\right)\).
What does "x-intercept" mean?
The x-intercept is the point where the graph crosses the x-axis, so the y-coordinate is zero. Solve the equation with \(y=0\) to find the x-value.
What is the y-intercept of \(y=18x+6\)?.
The y-intercept is the value when \(x=0\). Plugging in gives \(y=6\), so the y-intercept is \( \left(0,6\right)\).
What is the slope and what does it tell me?
The slope is 18 (from \(y=mx+b\) with \(m=18\)). It means for each increase of 1 in \(x\), \(y\) increases by 18; the line is very steep upward.
How can I graph this line quickly?
Plot the y-intercept \(\left(0,6\right)\), then use the slope rise/run = 18/1 to go up 18 units and right 1 unit (or reduce to up 2 right \(1/9\)), or use another point like the x-intercept \(\left(-\tfrac{1}{3},0\right)\) and draw the line through them.
Is the \(x\)-intercept the same as the root or zero of the function?
Is the \(x\)-intercept the same as the root or zero of the function?
How do I check my answer algebraically?
Substitute \(x=-\tfrac{1}{3}\) into \(y=18x+6\): \(y=18(-\tfrac{1}{3})+6=-6+6=0\). Since \(y=0\), the intercept is correct.
What if the slope were zero or the line were vertical?
If slope \(m=0\) (horizontal), then either no x-intercept (if \(y\neq0\)) or every x (if \(y=0\)). For a vertical line \(x=c\), the x-intercept is \((c,0)\) only if the line crosses the x-axis, i.e., if \(0\) is on the line.
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