Algebra 1 : How to find slope of a line

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #161 : How To Find Slope Of A Line

Give the slope of the line of the equation

\(\displaystyle 9y - 4x = 30\)

Possible Answers:

\(\displaystyle -\frac{9}{4}\)

\(\displaystyle -\frac{4}{9}\)

\(\displaystyle \frac{9}{4}\)

\(\displaystyle \frac{4}{9}\)

\(\displaystyle -36\)

Correct answer:

\(\displaystyle \frac{4}{9}\)

Explanation:

Rewrite the equation in slope-intercept form \(\displaystyle y = mx+b\):

\(\displaystyle 9y - 4x = 30\)

\(\displaystyle 9y - 4x + 4x = 30+ 4x\)

\(\displaystyle 9y = 4x+ 30\)

\(\displaystyle 9y \div 9 = (4x+ 30) \div 9\)

\(\displaystyle y = \frac{4}{9} x + \frac{30}{9}\)

\(\displaystyle y = \frac{4}{9} x + \frac{10}{3}\)

The coefficient of \(\displaystyle x\), which is \(\displaystyle \frac{4}{9}\), is the slope.

Example Question #231 : Slope And Line Equations

Give the slope of the line of the equation

\(\displaystyle x= 5y - 17\)

Possible Answers:

\(\displaystyle -5\)

\(\displaystyle 5\)

\(\displaystyle \frac{1}{5}\)

\(\displaystyle -\frac{1}{5}\)

The line has no slope

Correct answer:

\(\displaystyle \frac{1}{5}\)

Explanation:

Rewrite the equation in slope-intercept form \(\displaystyle y = mx+b\):

\(\displaystyle x= 5y - 17\)

\(\displaystyle 5y - 17 = x\)

\(\displaystyle 5y - 17 + 17 = x + 17\)

\(\displaystyle 5y = x + 17\)

\(\displaystyle 5y \div 5 = (x + 17) \div 5\)

\(\displaystyle y= \frac{1}{5}x + \frac{17 }{5}\)

The coefficient of \(\displaystyle x\), which is \(\displaystyle \frac{1}{5}\), is the slope.

Example Question #162 : How To Find Slope Of A Line

Give the slope of the line of the equation

\(\displaystyle 7x + 6y = 33\)

Possible Answers:

\(\displaystyle \frac{6}{7}\)

\(\displaystyle -\frac{7}{6}\)

\(\displaystyle \frac{7}{6}\)

\(\displaystyle -\frac{6}{7}\)

The correct answer is not among the other choices.

Correct answer:

\(\displaystyle -\frac{7}{6}\)

Explanation:

Rewrite the equation in slope-intercept form \(\displaystyle y = mx+b\):

\(\displaystyle 7x + 6y = 33\)

\(\displaystyle 7x + 6y - 7x = 33- 7x\)

\(\displaystyle 6y = -7x + 33\)

\(\displaystyle 6y \div 6 =( -7x + 33) \div 6\)

\(\displaystyle y = -\frac{7}{6}x + \frac{33}{6}\)

The coefficient of \(\displaystyle x\), which is \(\displaystyle -\frac{7}{6}\), is the slope.

Example Question #163 : How To Find Slope Of A Line

Find the slope of a line given by the equation:  

\(\displaystyle y=2(2x-3)+4x\)

Possible Answers:

\(\displaystyle 4\)

\(\displaystyle 2\)

\(\displaystyle 8\)

\(\displaystyle \textup{Slope is unknown.}\)

\(\displaystyle 6\)

Correct answer:

\(\displaystyle 8\)

Explanation:

In order to find the slope of this equation, we will need to put this in y-intercept form, \(\displaystyle y=mx+b\).

Simplify the equation by distribution and combine like-terms.

\(\displaystyle y=2(2x)+2(-3)+4x\)

Simplify the parentheses.

\(\displaystyle y=4x-6+4x\)

Add like terms.

\(\displaystyle y=8x-6\)

The slope is \(\displaystyle 8\).

Example Question #234 : Slope And Line Equations

Given the following equation, \(\displaystyle \frac{1}{3}x+\frac{1}{4}y=1\), what is the slope of this line?

Possible Answers:

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

\(\displaystyle -\frac{4}{3}\)

\(\displaystyle -\frac{3}{4}\)

\(\displaystyle \frac{1}{12}\)

\(\displaystyle \frac{4}{3}\)

Correct answer:

\(\displaystyle -\frac{4}{3}\)

Explanation:

The given equation is currently in standard form.  In order to find the slope, we will need to isolate the \(\displaystyle y\) variable and put the equation in slope-intercept form.

The slope-intercept form is:  \(\displaystyle y=mx+b\)

Subtract \(\displaystyle \frac{1}{3}x\) from both sides.

\(\displaystyle \frac{1}{3}x+\frac{1}{4}y-\frac{1}{3}x=1-\frac{1}{3}x\)

Simplify both sides.

\(\displaystyle \frac{1}{4}y=1-\frac{1}{3}x\)

Multiply by four on both sides.

\(\displaystyle 4(\frac{1}{4}y)=4(1-\frac{1}{3}x)\)

Distribute both sides.

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

Rearrange the terms.

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

The slope is:  \(\displaystyle -\frac{4}{3}\)

Example Question #235 : Slope And Line Equations

What is the slope of the following set of coordinates?

\(\displaystyle (2,0)\) and \(\displaystyle (2,1)\)

Possible Answers:

\(\displaystyle m=0\)

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

\(\displaystyle m=2\)

Undefined

\(\displaystyle m=1\)

Correct answer:

Undefined

Explanation:

To solve this problem you need to know the slope formula and set it up accordingly:

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

 \(\displaystyle \frac{1-0}{2-2}\)

This simplifies to:

\(\displaystyle \frac{1}{0}\)  and because 0 is in the denominator this slope is undefined.

Example Question #236 : Slope And Line Equations

Find the slope of a line if the points given are \(\displaystyle (6,9)\) and \(\displaystyle (-3,6)\).

Possible Answers:

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

\(\displaystyle 3\)

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

\(\displaystyle -\frac{3}{2}\)

\(\displaystyle \frac{3}{2}\)

Correct answer:

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

Explanation:

Write the formula to find the slope given two points.

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

Substitute the given points into this formula.

\(\displaystyle m=\frac{6-9}{-3-6}\)

Simplify this fraction and reduce.

\(\displaystyle m=\frac{-3}{-9}= \frac{1}{3}\)

Example Question #237 : Slope And Line Equations

Points A: \(\displaystyle (3,2)\) and B: \(\displaystyle (4,2)\) lie on the same line. What is the slope of this line?

Possible Answers:

\(\displaystyle 1\)

Undefined

\(\displaystyle -1\)

\(\displaystyle 3\)

\(\displaystyle 0\)

Correct answer:

\(\displaystyle 0\)

Explanation:

The slope equation is:

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

Plugging these points:

\(\displaystyle \frac{2-2}{4-3}\)

\(\displaystyle \frac{0}{1}=0\)

Example Question #238 : Slope And Line Equations

Find the slope between the following coordinate points:

\(\displaystyle (2,3)\) and \(\displaystyle (4,5)\)

Possible Answers:

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

\(\displaystyle \frac{1}{6}\)

\(\displaystyle 1\)

\(\displaystyle 2\)

\(\displaystyle \frac{1}{4}\)

Correct answer:

\(\displaystyle 1\)

Explanation:

In order to find the slope, we must find the difference in \(\displaystyle y\) coordinates and divide this number by the difference between the \(\displaystyle x\) coordinates. 

\(\displaystyle (2,3)(4,5)\)

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

Example Question #239 : Slope And Line Equations

Find the slope between the following coordinate points:

\(\displaystyle (12,4)\) and \(\displaystyle (6,6)\)

Possible Answers:

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

\(\displaystyle 3\)

\(\displaystyle -3\)

\(\displaystyle 2\)

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

Correct answer:

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

Explanation:

In order to find the slope, we must find the difference in \(\displaystyle y\) coordinates and divide this number by the difference between the \(\displaystyle x\) coordinates. 

\(\displaystyle (12,4)(6,6)\)

\(\displaystyle \text{Slope}=\frac{6-4}{6-12}=\frac{2}{-6}=-\frac{1}{3}\)

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