Download presentation

Presentation is loading. Please wait.

1
**Learn to solve equations involving decimals.**

2
You can solve equations with decimals using inverse operations just as you solved equations with whole numbers. $ m = $69.95 –$45.20 –$45.20 m = $24.75

3
**Use inverse operations to get the variable alone on one side of the equation.**

Remember!

4
**Additional Example 1A: Solving One-Step Equations with Decimals**

Solve the equation. Check your answer. k – 6.2 = 9.5 k – 6.2 = 9.5 6.2 is subtracted from k. + 6.2 + 6.2 Add 6.2 to both sides to undo the subtraction. k = 15.7 Check k – 6.2 = 9.5 Substitute 15.7 for k in the equation. 15.7 – 6.2 = 9.5 ? 9.5 = 9.5 ? 15.7 is the solution.

5
**Additional Example 1B: Solving One-Step Equations with Decimals**

Solve the equation. Check your answer. 6k = 7.2 k is multiplied by 6. 6k = 7.2 6k = 7.2 Divide both sides by 6 to undo the multiplication. 6 6 k = 1.2 Check 6k = 7.2 Substitute 1.2 for k in the equation. 6(1.2) = 7.2 ? 7.2 = 7.2 ? 1.2 is the solution.

6
**Additional Example 1C: Solving One-Step Equations with Decimals**

Solve the equation. Check your answer. m = 0.6 m is divided by 7. 7 m 7 · 7 = 0.6 · 7 Multiply both sides by 7 to undo the division. m = 4.2 Check = 0.6 m 7 Substitute 4.2 for m in the equation. = 0.6 4.2 7 ? 0.6 = 0.6 ? 4.2 is the solution.

7
**Solve the equation. Check your answer.**

Check It Out: Example 1A Solve the equation. Check your answer. n – 3.7 = 8.6 n – 3.7 = 8.6 3.7 is subtracted from n. + 3.7 + 3.7 Add 3.7 to both sides to undo the subtraction. n = 12.3 Check n – 3.7 = 8.6 Substitute 12.3 for n in the equation. 12.3 – 3.7 = 8.6 ? 8.6 = 8.6 ? 12.3 is the solution.

8
**Solve the equation. Check your answer.**

Check It Out: Example 1B Solve the equation. Check your answer. 7h = 8.4 h is multiplied by 7. 7h = 8.4 7h = 8.4 Divide both sides by 7 to undo the multiplication. 7 7 h = 1.2 Check 7h = 8.4 Substitute 1.2 for h in the equation. 7(1.2) = 8.4 ? 8.4 = 8.4 ? 1.2 is the solution.

9
**Solve the equation. Check your answer.**

Check It Out: Example 1C Solve the equation. Check your answer. w = 0.3 w is divided by 9. 9 w 9 · 9 = 0.3 · 9 Multiply both sides by 9 to undo the division. w = 2.7 Check = 0.3 w 9 Substitute 2.7 for w in the equation. = 0.3 2.7 9 ? 0.3 = 0.3 ? 2.7 is the solution.

10
**The area of a rectangle is its length times its width.**

A = lw Remember! w l

11
**Additional Example 2A: Measurement Application**

The area of Emily’s floor is m2. If its length is 4.5 meters, what is its width? area = length · width 33.75 = 4.5 · w Write the equation for the problem. Let w be the width of the room. 33.75 = 4.5w 33.75 = 4.5w Divide both sides by 4.5 to undo the multiplication. 4.5 4.5 7.5 = w The width of Emily’s floor is 7.5 meters.

12
**Additional Example 2B: Measurement Application**

If carpet costs $23 per square meter, what is the total cost to carpet the floor? total cost = area · cost of carpet per square meter Let C be the total cost. Write the equation for the problem. C = · 23 C = Multiply. The cost of carpeting the floor is $

13
Check It Out: Example 2A The area of Yvonne’s bedroom is ft2. If its length is 12.5 feet, what is its width? area = length · width = 12.5 · w Write the equation for the problem. Let w be the width of the room. = 12.5w = 12.5w Divide both sides by 12.5 to undo the multiplication. 12.5 12.5 14.5 = w The width of Yvonne’s bedroom is 14.5 feet.

14
Check It Out: Example 2B If carpet costs $4 per square foot, what is the total cost to carpet the bedroom? total cost = area · cost of carpet per square foot Let C be the total cost. Write the equation for the problem. C = · 4 C = 725 Multiply. The cost of carpeting the bedroom is $725.

Similar presentations

© 2024 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google