Question

Difficulty: MediumCoordinate Geometry and Lines

In the xyxy-plane, line kk passes through the point (2,−3)(2, -3) and has a slope of −43-\frac{4}{3}. Line mm is parallel to line kk and has an xx-intercept at (6,0)(6, 0). What is the yy-intercept of line mm?

  1. 88Answer
  2. B
    −8-8
  3. C
    92\frac{9}{2}
  4. D
    34\frac{3}{4}
  5. E
    −6-6

Answer

The yy-intercept of line mm is 88.
Parallel lines have equal slopes, so line mm has slope m=−43m = -\frac{4}{3}. An xx-intercept of (6,0)(6, 0) means line mm passes through (6,0)(6, 0). Substituting x=6x = 6, y=0y = 0, and m=−43m = -\frac{4}{3} into y=mx+by = mx + b gives 0=−43(6)+b0 = -\frac{4}{3}(6) + b, which simplifies to 0=−8+b0 = -8 + b, so b=8b = 8. Thus, the yy-intercept is 88.

Step-by-Step Solution

1
Determine the slope of line mm
The slope of line mm is −43-\frac{4}{3}.
Parallel lines in the coordinate plane have identical slopes. Since line kk has a slope of −43-\frac{4}{3}, line mm must also have a slope of −43-\frac{4}{3}.
2
Use the xx-intercept (6,0)(6, 0) to solve for the yy-intercept bb of line mm
0=−43(6)+b  ⟹  0=−8+b  ⟹  b=80 = -\frac{4}{3}(6) + b \implies 0 = -8 + b \implies b = 8.
Substitute x=6x = 6, y=0y = 0, and slope m=−43m = -\frac{4}{3} into the slope-intercept form y=mx+by = mx + b.

Key Concept

Parallel line slopes and slope-intercept form
Estimated Time:1m 15s
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