ISEE Lower Level Quantitative : How to find a line on a coordinate plane

Study concepts, example questions & explanations for ISEE Lower Level Quantitative

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Example Questions

Example Question #141 : Geometry

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Which equation of a line is parallel to line segment \(\displaystyle \bar{AB}\)?  

Possible Answers:

\(\displaystyle y=\frac{5}{12}+4\)

\(\displaystyle y=\frac{13}{9}+5\)

\(\displaystyle y=\frac{9}{13}-8\)

\(\displaystyle y=-\frac{9}{13}-6\)

Correct answer:

\(\displaystyle y=\frac{9}{13}-8\)

Explanation:

In order for the equation to represent a line that is parallel to the line that is shown, the equation must have the same slope as line segment \(\displaystyle \bar{AB}\)

Since, line segment \(\displaystyle \bar{AB}\) has a slope of \(\displaystyle \frac{9}{13}\), the correct equation is: \(\displaystyle y=\frac{9}{13}-8\)

Example Question #1 : How To Find A Line On A Coordinate Plane

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The points in the above line segment are apart of which of the following linear equations? 

Possible Answers:

\(\displaystyle x=-7\)

\(\displaystyle x=7\)

\(\displaystyle y=7\)

\(\displaystyle y=-7\)

Correct answer:

\(\displaystyle y=-7\)

Explanation:

The above line segment is a horizontal line that passes through the \(\displaystyle y\) axis at \(\displaystyle -7.\) Since this line is horizontal, it does not have a slope. Therefore, \(\displaystyle y=-7\) is the correct answer. 

Example Question #1 : How To Find A Line On A Coordinate Plane

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Which of the following linear equations is perpendicular to the line segment shown above? 

Possible Answers:

\(\displaystyle y=-7\)

\(\displaystyle x=-3\)

\(\displaystyle y=-\frac{1}{2}-7\)

\(\displaystyle y=7\)

Correct answer:

\(\displaystyle x=-3\)

Explanation:

Since the line segment is horizontal, the equation that is perpendicular to the segment must run vertically. The only linear equation that runs vertically (perpendicular to \(\displaystyle y=-7\)) is \(\displaystyle x=-3\).

Example Question #144 : Geometry

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At what coordinate point does the line \(\displaystyle x=-3\) intersect with the line segment shown above? 

Possible Answers:

\(\displaystyle (3,-7)\)

\(\displaystyle (3,7)\)

\(\displaystyle (-7,-3)\)

\(\displaystyle (-3,-7)\)

Correct answer:

\(\displaystyle (-3,-7)\)

Explanation:

Since, \(\displaystyle x=-3\) is perpendicular to \(\displaystyle y=-7\) the points must cross at \(\displaystyle (-3,-7)\), because it is the only coordinate point that both lines pass through. 

Example Question #145 : Geometry

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At which coordinate point does this line segment cross the \(\displaystyle x\)-axis? 

Possible Answers:

\(\displaystyle (0,-2)\)

\(\displaystyle (0,3)\)

\(\displaystyle (3,0)\)

\(\displaystyle (-3,0)\)

Correct answer:

\(\displaystyle (3,0)\)

Explanation:

Keep in mind that the values in the coordinate points are \(\displaystyle (x,y)\), thus the point \(\displaystyle (3,0)\) is the point at which the line segment passes through the \(\displaystyle x\) axis. 

Example Question #1 : How To Find A Line On A Coordinate Plane

Find the equation that represents a line that has a \(\displaystyle y\) intercept of \(\displaystyle -7\).

Possible Answers:

\(\displaystyle y=\frac{3}{4}x-7\)

\(\displaystyle y=\frac{3}{4}x+7\)

\(\displaystyle y=\frac{3}{4}x-5\)

\(\displaystyle y=\frac{3}{4}x+5\)

Correct answer:

\(\displaystyle y=\frac{3}{4}x-7\)

Explanation:

To identify the correct equation, apply the formula \(\displaystyle y=mx+b\), where \(\displaystyle m\) represents the slope of the line and \(\displaystyle b=\) the \(\displaystyle y\) intercept. 

Thus, the line that passes through the \(\displaystyle y\) axis at \(\displaystyle (0,-7)\) is \(\displaystyle y=\frac{3}{4}x-7\)

Example Question #7 : How To Find A Line On A Coordinate Plane

Which of the following equations of a line has the steepest slope? 

Possible Answers:

\(\displaystyle y=-\frac{8}{3}x+4\)

\(\displaystyle y=\frac{8}{4}x+4\)

\(\displaystyle y=-\frac{3}{4}x+8\)

\(\displaystyle y=-\frac{3}{8}x+4\)

Correct answer:

\(\displaystyle y=-\frac{8}{3}x+4\)

Explanation:

To find which equation of a line has the steepest slope, apply the formula: \(\displaystyle y=mx+b\), where \(\displaystyle m\) represents the slope of the line and \(\displaystyle b\) represents the \(\displaystyle y\) intercept.

Also, note that \(\displaystyle m=\frac{rise}{run}\), meaning the change in the \(\displaystyle y\) value, over the change in the \(\displaystyle x\) value. 

The equation that has the largest absolute value of m is the equation that has the steepest slope.

Thus, the equation \(\displaystyle y=-\frac{8}{3}x+4\) has the steepest slope, because in order to go from one point to the next move a vertical distance of \(\displaystyle 8\) and a horizontal distance of \(\displaystyle 3\) which is larger than any of the other choices. 

Example Question #901 : Isee Lower Level (Grades 5 6) Quantitative Reasoning

Find the slope of the line that passes through the coordinate points \(\displaystyle (-3,4)\) and \(\displaystyle (2,-1)\).

Possible Answers:

\(\displaystyle \frac{1}{2}\)

\(\displaystyle -\frac{1}{2}\)

\(\displaystyle -1\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle -1\)

Explanation:

To find the slope of the line that passes through these two coordinate points, apply the formula: 

\(\displaystyle Slope=\frac{y_2-y_1}{x_2-x_1}\)

Thus the correct answer is:

\(\displaystyle \frac{ -1-4}{2--3}=\frac{-5}{5}=-\frac{5}{5}=-1\)

Example Question #9 : How To Find A Line On A Coordinate Plane

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Line segment \(\displaystyle \bar{AB}\) has endpoints \(\displaystyle (-6,-3)\) and \(\displaystyle (7,6)\). What is the slope of the line segment? 

Possible Answers:

\(\displaystyle \frac{1}{3}\)

\(\displaystyle -\frac{9}{13}\)

\(\displaystyle \frac{9}{13}\)

\(\displaystyle \frac{13}{9}\)

Correct answer:

\(\displaystyle \frac{9}{13}\)

Explanation:

To find the slope of the line that passes through these two coordinate points, apply the formula: 

\(\displaystyle Slope=\frac{y_2-y_1}{x_2-x_1}\)

Thus the correct answer is:
\(\displaystyle \frac{6--3}{7--6}=\frac{6+3}{7+6}=\frac{9}{13}\)

Example Question #152 : Geometry

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Find the length of the line segment above. 

 

Possible Answers:

\(\displaystyle 23\)

\(\displaystyle 17\)

\(\displaystyle 9\)

\(\displaystyle 8\)

Correct answer:

\(\displaystyle 17\)

Explanation:

To find the length of this line segment find the difference between each of the two end points \(\displaystyle x\) values, since they have the same \(\displaystyle y\) value. 

The difference between \(\displaystyle -8\) and \(\displaystyle 9\) is \(\displaystyle 17\).

\(\displaystyle 9-(-8)=9+8=17\)

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