Study on the flyISEE UpperQuantitative ReasoningCoordinate geometry (lines and slope)

Quantitative Reasoning

Coordinate geometry (lines and slope) — ISEE Upper practice questions

  • 37 questions on the paper
  • 59 practice questions in the app
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What this topic is

Coordinate geometry (lines and slope) on the ISEE Upper Quantitative Reasoning section covers points, intercepts, slope, and the comparison of lines in the plane.

A student must find where a segment meets an axis, count lattice points on a line, and judge whether two given lines are parallel, perpendicular, or intersecting. Items usually appear as short word problems or which-of-the-following statements. Common traps include swapping intercepts, reversing rise over run, and treating distance from the origin as a single coordinate instead of using the distance formula.

Choices typically offer points, whole-number counts, or brief claims about the two lines.

Sample questions

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Question 1Harder

Points with positive integer coordinates lie on the line x+y=9x+y=9. How many of these points are more than 7 units from the origin?

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Answer: B — 4

The possible points are (1,8)(1,8) through (8,1)(8,1). Only (1,8)(1,8), (2,7)(2,7), (7,2)(7,2), and (8,1)(8,1) have x2+y2>49x^2+y^2>49, so there are 4 such points.

Question 2Mid

Line pp passes through (2,1)(2,1) and (6,9)(6,9). Line qq passes through (0,4)(0,4) and (4,2)(4,2). Which of the following is true?

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Answer: B — pp and qq are perpendicular

The slope of pp is 9162=2\dfrac{9-1}{6-2}=2. The slope of qq is 2440=12\dfrac{2-4}{4-0}=-\dfrac{1}{2}. The product of the slopes is 2×(12)=12\times\left(-\dfrac{1}{2}\right)=-1, so the lines are perpendicular. The intercepts of the two lines are not the same.

Question 3Mid

Segment JK\overline{JK} joins J(2,3)J(2,3) and K(4,1)K(-4,-1). At which point does JK\overline{JK} intersect the xx-axis?

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Answer: C — (52,0)\left(-\dfrac{5}{2},0\right)

The slope of JKJK is 1342=23\dfrac{-1-3}{-4-2}=\dfrac{2}{3}, so its equation is y3=23(x2)y-3=\dfrac{2}{3}(x-2). On the xx-axis, y=0y=0, giving 3=23(x2)-3=\dfrac{2}{3}(x-2) and x=52x=-\dfrac{5}{2}. The intersection is (52,0)\left(-\dfrac{5}{2},0\right).

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Practice 59 Coordinate geometry (lines and slope) questions in the app

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