Math Problem Statement

This table gives a few (x,y)pairs of a line in the coordinate plane. (x) (y)][33] [-22] [52] [-33] [71] [-44] What is the [x]-intercept of the line?

Solution

To find the xx-intercept of the line, we need to identify the point where the line crosses the xx-axis. This occurs when y=0y = 0.

Looking at the given points, we have:

  • (33,22)(33, -22)
  • (52,33)(52, -33)
  • (71,44)(71, -44)

None of these points have y=0y = 0, so the line doesn't cross the xx-axis at these points.

We can use the equation of the line (in slope-intercept form, y=mx+by = mx + b) to determine the xx-intercept.

Steps to find the xx-intercept:

  1. Find the slope of the line (m): We can use two points, say (33,22)(33, -22) and (52,33)(52, -33), to calculate the slope mm.

    m=y2y1x2x1=33(22)5233=33+225233=1119m = \frac{y_2 - y_1}{x_2 - x_1} = \frac{-33 - (-22)}{52 - 33} = \frac{-33 + 22}{52 - 33} = \frac{-11}{19}

    So, the slope is m=1119m = \frac{-11}{19}.

  2. Use the point-slope form to find the equation of the line: The point-slope form of a line is: yy1=m(xx1)y - y_1 = m(x - x_1) Using point (33,22)(33, -22) and the slope m=1119m = \frac{-11}{19}, we substitute into the equation: y(22)=1119(x33)y - (-22) = \frac{-11}{19}(x - 33) Simplify: y+22=1119(x33)y + 22 = \frac{-11}{19}(x - 33) Distribute the slope on the right side: y+22=1119x+11×3319y + 22 = \frac{-11}{19}x + \frac{11 \times 33}{19} Simplifying: y+22=1119x+36319y + 22 = \frac{-11}{19}x + \frac{363}{19} Now, solve for yy: y=1119x+3631922y = \frac{-11}{19}x + \frac{363}{19} - 22 Convert 22 to a fraction with denominator 19: 22=4181922 = \frac{418}{19} Substituting: y=1119x+3631941819y = \frac{-11}{19}x + \frac{363}{19} - \frac{418}{19} y=1119x5519y = \frac{-11}{19}x - \frac{55}{19}

  3. Find the xx-intercept: The xx-intercept occurs when y=0y = 0. Set y=0y = 0 in the equation: 0=1119x55190 = \frac{-11}{19}x - \frac{55}{19} Multiply both sides by 19 to eliminate the denominator: 0=11x550 = -11x - 55 Solve for xx: 11x=5511x = -55 x=5x = -5

Thus, the xx-intercept of the line is at x=5x = -5.

Would you like a more detailed breakdown of any part of this process? Or do you have any follow-up questions?

Related Questions:

  1. How would the equation change if a different pair of points were used?
  2. How do you find the slope when both coordinates of one point are negative?
  3. How does the slope affect the steepness of a line?
  4. What happens if the slope is 0? How does that change the equation?
  5. How can you verify the line equation using a third point on the line?

Tip: To quickly check your slope calculation, ensure that the change in yy is divided by the change in xx, not the other way around!

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Math Problem Analysis

Mathematical Concepts

Linear Equations
Slope-Intercept Form
Coordinate Geometry

Formulas

y = mx + b
Slope Formula: m = (y2 - y1) / (x2 - x1)
Point-Slope Form: y - y1 = m(x - x1)

Theorems

Slope formula
Point-slope form of a line

Suitable Grade Level

Grades 8-10