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 #1 : How To Find Slope Of A Line

What is the slope of the equation 4x + 3y = 7?

Possible Answers:

4/3

–4/3

–7/3

–3/4

3/4

Correct answer:

–4/3

Explanation:

We should put this equation in the form of y = mx + b, where m is the slope.

We start with 4x + 3y = 7.

Isolate the y term: 3y = 7 – 4x

Divide by 3: y = 7/3 – 4/3 * x

Rearrange terms: y = –4/3 * x + 7/3, so the slope is –4/3.

Example Question #2 : How To Find Slope Of A Line

Find the slope of the line through the points (6,2) and (3,4).

Possible Answers:

\displaystyle \frac{3}{2}

\displaystyle 6

\displaystyle \frac{2}{3}

\displaystyle -\frac{2}{3}

\displaystyle -\frac{3}{2}

Correct answer:

\displaystyle -\frac{2}{3}

Explanation:

The equation for slope is \displaystyle \frac{(y_2-y_1)}{(x_2-x_1)}. You plug in the coordinates from the points given you, and get \displaystyle \frac{(4-2)}{(3-6)}, giving you \displaystyle \frac{2}{-3}. Note that it does not matter which point you use as point 1 and point 2, as long as you are consistent.

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

(6,2) = (x1,y1)

(3,4) = (x2,y2)

\displaystyle \frac{(4-2)}{(3-6)}=\frac{2}{-3}=-\frac{2}{3}

Example Question #1 : How To Find Slope Of A Line

Given the line 4y = 2x + 1, what is the slope of this line?

Possible Answers:

–1/4

–2

1/4

1/2

2

Correct answer:

1/2

Explanation:

4y = 2x + 1 becomes y = 0.5x + 0.25. We can read the coefficient of x, which is the slope of the line.

4y = 2x + 1

(4y)/4 = (2x)/4 + (1)/4

y = 0.5x + 0.25

y = mx + b, where the slope is equal to m.

The coefficient is 0.5, so the slope is 1/2.

Example Question #1 : How To Find Slope Of A Line

What is the slope of the line containing the points (7,12) and (91,32).

Possible Answers:

\displaystyle \frac{5}{21}

\displaystyle \frac{44}{49}

\displaystyle \frac{51}{30}

\displaystyle \frac{3}{32}

Correct answer:

\displaystyle \frac{5}{21}

Explanation:

To find the slope of a line you must first assign variables to each point. It does not matter which points get which variables as long as you keep the \displaystyle x_{1} and \displaystyle y_{1} and \displaystyle x_{2} and \displaystyle y_{2} consistent when you plug them into the equation.

Then we plug in the variables to this equation where \displaystyle m represents the slope.\displaystyle m=\frac{(y_{2}-y_{1})}{(x_{2}-x_{1})}

Then we plug in our points for \displaystyle x_{1},x_{2},y_{1},and\ y_{2} and the example looks like\displaystyle m=\frac{(32-12)}{(91-7)}

Then we perform the necessary subtraction and division to find an answer of \displaystyle m=\frac{20}{84}=\frac{5}{21}

Example Question #71 : Slope And Line Equations

Possible Answers:

\displaystyle \frac{13}{3}

\displaystyle -\frac{3}{4}

\displaystyle \frac{4}{3}

\displaystyle -\frac{4}{3}

\displaystyle \frac{3}{4}

Correct answer:

\displaystyle \frac{4}{3}

Explanation:

\displaystyle 3y-4x=13

\displaystyle 3y=4x+13

Example Question #2 : How To Find Slope Of A Line

Which of the following is an example of an equation written in slope-intercept form?

Possible Answers:

\displaystyle -y=x-4

\displaystyle y=-x+4

\displaystyle y+x-4=0

\displaystyle y+x=4

Correct answer:

\displaystyle y=-x+4

Explanation:

Slope intercept form is \displaystyle y=mx+b, where \displaystyle m is the slope and \displaystyle b is the y-intercept.

\displaystyle y=-x+4 is the correct answer. The line has a slope of \displaystyle -1 and a y-intercept equal to \displaystyle 4.

Example Question #1 : How To Find Slope Of A Line

If (1,2) and (4,6) are on the same line, what is the slope of the line?

Possible Answers:

\displaystyle 2

\displaystyle 1

\displaystyle \frac{3}{4}

\displaystyle \frac{4}{3}

\displaystyle \frac{1}{2}

 

Correct answer:

\displaystyle \frac{4}{3}

Explanation:

\displaystyle m=slope=\frac{\Delta y}{\Delta x}=\frac{\left ( y_{2}-y_{1}\right )}{\left ( x_{2}-x_{1}\right )}=

\displaystyle \frac{\left ( 6-2\right )}{\left ( 4-1\right )}=\frac{4}{3}

Example Question #1 : How To Find Slope Of A Line

The equation of a line is:

\displaystyle 5x+25y=14

What is the slope of the line?

Possible Answers:

\displaystyle \frac{14}{25}

 

\displaystyle \frac{1}{5}

 

\displaystyle -\frac{14}{25}

\displaystyle -\frac{1}{5}

\displaystyle 5

Correct answer:

\displaystyle -\frac{1}{5}

Explanation:

Solve the equation for \displaystyle y=mx+b

where \displaystyle m is the slope of the line:

\displaystyle 5x+25y=14

\displaystyle 25y=-5x+14

\displaystyle y=-\left ( \frac{5}{25} \right )x+\frac{14}{25}=-\left ( \frac{1}{5} \right )x+\frac{14}{25}

\displaystyle Slope=-\frac{1}{5}

 

Example Question #3 : How To Find Slope Of A Line

A line passes through the points \displaystyle (-1,4) and \displaystyle (4,-9).  What is its slope?

Possible Answers:

\displaystyle \frac{5}{13}

\displaystyle -\frac{13}{5}

-\displaystyle -\frac{5}{13}

\displaystyle \frac{13}{5}

Correct answer:

\displaystyle -\frac{13}{5}

Explanation:

The slope is the rise over the run.  The line drops in \displaystyle y-coordinates by 13 while gaining 5 in the \displaystyle x-coordinates.

Example Question #1 : How To Find Slope Of A Line

What is the slope of the line \displaystyle 2y-4x=12?

Possible Answers:

\displaystyle 2

\displaystyle 6

\displaystyle 2

\displaystyle -4

\displaystyle 4

Correct answer:

\displaystyle 2

Explanation:

You can rearrange \displaystyle 2y-4x=12 to get an equation resembling the \displaystyle y=mx+b formula by isolating the \displaystyle y. This gives you the equation \displaystyle y=2x+6. The slope of the equation is 2 (the \displaystyle m within the \displaystyle y=mx+b equation).

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