Algebra 1 : Algebra 1

Study concepts, example questions & explanations for Algebra 1

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Example Questions

Example Question #3 : How To Write Expressions And Equations

Translate this sentence into a mathematical equation:

Three less than five times a number is the same as two more than twice that number.

Possible Answers:

\displaystyle 5n-3 = 2n+2

\displaystyle 5n-3 = 2(n+2)

\displaystyle 5n-3 = 2n-2

\displaystyle 5(n-3) = 2n+2

\displaystyle 5n + 3 = 2n + 2

Correct answer:

\displaystyle 5n-3 = 2n+2

Explanation:

Three less than five times a number is the same as two more than twice that number.

Let the number be \displaystyle n.

"Three less than five times a number" translates into \displaystyle 5n-3.

"Is the same as" means equal to or "\displaystyle =".

"Two more than twice that number" means \displaystyle 2n+2.

Putting these together gives:

\displaystyle 5n-3 = 2n+2

Example Question #922 : Algebra 1

For the given equation determine the slope:

\displaystyle 3x-2y=5

Possible Answers:

\displaystyle -2

\displaystyle 3

\displaystyle \frac{2}{3}

\displaystyle 5

\displaystyle \frac{3}{2}

Correct answer:

\displaystyle \frac{3}{2}

Explanation:

By changing the equation to slope intercept form we get the following:

 

\displaystyle y = \frac{3}{2}x-5

 

Hence the slope is

\displaystyle m=\frac{3}{2}

Example Question #1 : How To Write Expressions And Equations

What is the slope and the \displaystyle x and \displaystyle y intercepts of a line which passes through \displaystyle \left ( -3,0 \right ) and \displaystyle \left ( -3,2 \right )?

Possible Answers:

slope = 0, x-int = 2, y-int = -3

slope = 0, x-int = -3, y-int = 2

slope = undefined, x-int 2, y-int = -3

slope = undefined, x-int = -3, y-int = none

slope = 1, x-int = 2, y-int = 2

Correct answer:

slope = undefined, x-int = -3, y-int = none

Explanation:

For a vertical line e.g. \displaystyle x=-3\displaystyle run=0 and \displaystyle \frac{rise}{0}=undefined

This line does not intersect the \displaystyle y-axis and hence there is no \displaystyle y-intercept.

Since the line passes through \displaystyle \left ( -3,0 \right ) hence the \displaystyle x-intercept \displaystyle =-3.

Example Question #923 : Algebra 1

Write the equation of a line with a slope of

 \displaystyle m=-\frac{3}{5} 

and passes through the point \displaystyle \left ( 3,-2 \right ).

Possible Answers:

\displaystyle y = \frac{-3}{5}x+1

\displaystyle \frac{3}{5}x +1

\displaystyle \frac{-3}{5}x -5

\displaystyle \frac{-3}{5}x-1

\displaystyle \frac{3}{5}x +1

Correct answer:

\displaystyle y = \frac{-3}{5}x+1

Explanation:

Here we use the point-slope formula of a line which is

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

By plugging in \displaystyle m\displaystyle x_{1}, and \displaystyle y_{1} values we get the following:

\displaystyle \left ( y-\left ( -2 \right ) \right ) = \frac{-3}{5}\left ( x-5 \right )

which is equal to

\displaystyle \left ( y+2 \right ) =\frac{-3}{5}\left ( x-5 \right )

When the above is simplified we get:

 

\displaystyle y = \frac{-3}{5}x +1

Example Question #4 : How To Write Expressions And Equations

Complete the missing information for the equation of the following line

\displaystyle y = \frac{-2}{3}x +5

and determine which one of the \displaystyle \left ( x,y \right ) coordinates is not a solution to the above equation.

\displaystyle \left ( 0,5 \right ),\left ( \frac{15}{2},0 \right ),\left ( -3,7 \right ),\left ( 3,3 \right ), \left ( -6,7 \right )

Possible Answers:

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

\displaystyle \left ( \frac{15}{2},0 \right )

\displaystyle \left ( 0,5 \right )

\displaystyle \left ( -6,7 \right )

\displaystyle \left ( 3,3 \right )

Correct answer:

\displaystyle \left ( -6,7 \right )

Explanation:

Replacing \displaystyle x with \displaystyle -6, one gets \displaystyle y=9 which tells us that \displaystyle \left ( -6,7 \right ) is not a solution.

Example Question #924 : Algebra 1

Convert the following into the standard form of a line:

 

\displaystyle y = \frac{-3}{5}x +2

Possible Answers:

\displaystyle 3x-5y=10

\displaystyle 5x+3y=10

\displaystyle 3x+5y=10

\displaystyle 3x-5y-10=0

\displaystyle 5x-3y=10

Correct answer:

\displaystyle 3x+5y=10

Explanation:

Multiplying each term of the given equation by the denominator of the slope which is 5 one gets :

 

\displaystyle 5y=-3x+10 

which can be written as


\displaystyle 3x+5y=10

Example Question #11 : How To Write Expressions And Equations

Equations of a line can be represented as follows:

(1) \displaystyle ax+by=c (standard form)

(2) \displaystyle y=mx+b (slope-intercept form)

(3) \displaystyle \left ( y-y_{1} \right ) = m\left ( x-x_{1} \right ) (point-slope form)

Possible Answers:

\displaystyle a

\displaystyle c

\displaystyle d

none of the above

\displaystyle b

Correct answer:

\displaystyle a

Explanation:

The equation of line \displaystyle a is

\displaystyle y=3

Hence 

\displaystyle rise = 0

and the

\displaystyle slope=0

Example Question #12 : How To Write Expressions And Equations

Find the equation of a line parallel to

\displaystyle y = -3x -3

and passes through \displaystyle \left ( 2,1 \right ).

Possible Answers:

\displaystyle y = -3x +b

\displaystyle y = \frac{1}{3}x + 7

\displaystyle y = -3x +7

\displaystyle y = -3x -7

\displaystyle y = 3x + 7

Correct answer:

\displaystyle y = -3x +7

Explanation:

The equation of a line parallel to the given line must be of the form:

\displaystyle y = -3x + b

Since the line passes through \displaystyle \left ( 2,1 \right ),

we can calculate \displaystyle b by replacing \displaystyle x with 2 and \displaystyle y with 1 which gives us the following

\displaystyle 1 = -3\left ( 2 \right ) + b

Solving for \displaystyle b gives us the following equation

\displaystyle y = -3x + 7

Example Question #11 : How To Write Expressions And Equations

Find the equation of a line perpendicular to

\displaystyle y = -3x -3

and passes through \displaystyle \left ( 2,1 \right )

Possible Answers:

\displaystyle y = \frac{1}{3}x - 3

\displaystyle y = -3x + 7

\displaystyle y = \frac{1}{3}x

\displaystyle y = \frac{1}{3}x + \frac{1}{3}

\displaystyle y = 3x + 3

Correct answer:

\displaystyle y = \frac{1}{3}x + \frac{1}{3}

Explanation:

The slope of a line perpendicular to

\displaystyle y = -3x - 3

which has a slope of \displaystyle -3, is the negative reciprocal of \displaystyle -3.

Hence we get

\displaystyle y = \frac{1}{3}x + b

Replacing \displaystyle x and \displaystyle y with the given point we get

\displaystyle 1 = \frac{1}{3}\left ( 2 \right ) + b

 

Solving for \displaystyle b we get

\displaystyle y = \frac{1}{3}x+ \frac{1}{3}

Example Question #12 : How To Write Expressions And Equations

Find the equation of a line perpendicular to

\displaystyle y = 3

and passes through \displaystyle \left ( -2, 2 \right )

Possible Answers:

\displaystyle x = 2

\displaystyle y = 2x

\displaystyle y = \frac{1}{3}x

\displaystyle y = 2

\displaystyle x = -2

Correct answer:

\displaystyle x = -2

Explanation:

Any line perpendicular to \displaystyle y = 3,

which is a horizontal line, must be a vertical line.

 

Since it passes through the point \displaystyle \left ( -2, 2 \right ) and must be perpendicular to

\displaystyle y = 3

The equation must be

\displaystyle x = -2

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