Writing & Solving Equations

Writing Equations

8th Grade Math Pod

Let's practice writing linear equations for real-life scenarios

Multiple Choice

Bruce bought two books. One book costs $4.00 more than three times the other. Together, the two books cost him $72.

Let x be the cost of the less expensive book.

• 3x+4 = 72 - 4

• x + 4 + 3x = 72

• x = 72 - 4

Multiple Choice

Janet is three years older than her sister Julie. Janet’s brother is eight years younger than their sister Julie. The sum of all of their ages is 𝟓𝟓 years.

Let x be Julie's age.

• (x + 3) + (x - 8) + x = 55

• x +3 - 8 = 55

• 3x + 8x = 55

Fill in the Blanks

Given that this is the correct equation, solve for Julie's age (x):

(x + 3) + (x - 8) + x = 55

Multiple Choice

The sum of three consecutive integers is 1,623.

Let x be the first integer.

• x³ = 1623

• x + 2x + 3x = 1623

• x + (x +1) + (x + 2) = 1623

Fill in the Blanks

Given that this is the correct equation, solve for the first integer (x):

x + (x +1) + (x + 2) = 1623

Multiple Choice

When you add 18 to 1/4 of a number, you get the number itself.

Let x be the number.

• 
  

  $\frac{1}{4}x\ +\ 18\ =\ x$

• 18x/4 = x

• x - 1/4 = 18x

Fill in the Blanks

Given that this is the correct equation, solve for our mystery number (x):

 $\frac{1}{4}x\ +\ 18\ =\ x$  

Let's do some speed-identifying of linear vs. non-linear expressions

Remember: linear expressions can only have x⁰ or x¹ !!

Multiple Choice

Linear or non-linear?

5x + 3

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

4x² - 9

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

11(x+2)

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

 $-8x\ +\ \frac{7}{9\ }-3$  

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

x²-9

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

0.31x + 7 - 4.2x

• Linear

• Non-linear

Multiple Choice

Linear or non-linear?

 $\left(\frac{x}{2}\right)^3\ +\ 1$  

• Linear

• Non-linear

Nice job! Now let's check our understanding with a Quizizz game :)

https://quizizz.com/admin/quiz/5d79246e68afb1001bfc7743/solving-linear-equations