Download presentation

Presentation is loading. Please wait.

Published byDomenic Allam Modified over 3 years ago

1
**Solve by Substitution: Isolate one variable in an equation **

Substitute into the other equation with ( ) Solve the second equation Plug answer into first equation to find other variable Created by Gregory Fisher. Problems taken from Glencoe Algebra II Workbook 3.2.

2
**X – 3y = 16 4x – y = 9 -y = 9 – 4x y = -9 + 4x X – 3(-9 + 4x) = 16**

1) Isolate one variable in an equation 2) Substitute into the other equation with ( ) 3) Solve the second equation 4) Plug answer into first equation to find other variable Y=-9+4(1) Y=-5 (1,-5) Consistent Independent

3
**5) 2m + n = 6 5m + 6n = 1 n = 6 – 2m 5m + 6(6 – 2m) = 1**

(5,-4) Consistent Independent

4
**7) u – 2v = 1/2 -u + 2v = 5 u = 1/2 + 2v -(1/2 + 2v) + 2v = 5**

0 = 5.5 No Solution! Inconsistent

5
Solve by Elimination Multiply one or both equations so that one of the variables is the additive inverse of the other one Add the two equations together Solve the equation Substitute answer into an equation and solve

6
**11) 2m – n = -1 3m + 2n = 30 4m – 2n = -2 3m + 2n = 30 7m = 28 m=4**

Multiply top by 2 4m – 2n = -2 3m + 2n = 30 Solve by Elimination 1) Multiply one or both equations so that one of the variables is the additive inverse of the other one 2) Add the two equations together 3) Solve the equation 4) Substitute answer into an equation and solve 7m = 28 m=4 2(4) – n = -1 8 – n = -1 –n = -9 n = 9

7
**25) 5g + 4k = 10 -3g – 5k = 7 25g + 20k =50 -12g- 20k =28 13g = 78 g=6**

Multiply top by 5 Multiply bottom by 4 25g + 20k =50 -12g- 20k =28 Solve by Elimination 1) Multiply one or both equations so that one of the variables is the additive inverse of the other one 2) Add the two equations together 3) Solve the equation 4) Substitute answer into an equation and solve 13g = 78 g=6 5(6) + 4k = 10 30+ 4k = 10 4k = -20 k = -5 (6,-5)

8
**14) 2x - y = -4 -4x +2y =6 4x – 2y =-8 -4x+2y =12 0x = 4 0=4**

Multiply top by 2 4x – 2y =-8 -4x+2y =12 Solve by Elimination 1) Multiply one or both equations so that one of the variables is the additive inverse of the other one 2) Add the two equations together 3) Solve the equation 4) Substitute answer into an equation and solve 0x = 4 0=4 Inconsistent

9
**When is it best to use each method….**

Substitution: When it’s easy to isolate one variable Elimination: When it’s not easy to isolate one variable Or you just want the value of one variable (Eliminate the other one)

10
**Check for Understanding**

What must you multiply the top equation by to eliminate the x? 5x – 3y = 12 15x – 6y = 2 By -3 to make -15 2) What will y be equal to in the second equation to solve by substitution? 5x – 3y = 12 15x – y = 2 2) -y=2 - 15x Y = x

Similar presentations

OK

Using Lowest Common Denominator to add and subtract fractions

Using Lowest Common Denominator to add and subtract fractions

© 2018 SlidePlayer.com Inc.

All rights reserved.

To ensure the functioning of the site, we use **cookies**. We share information about your activities on the site with our partners and Google partners: social networks and companies engaged in advertising and web analytics. For more information, see the Privacy Policy and Google Privacy & Terms.
Your consent to our cookies if you continue to use this website.

Ads by Google

Ppt on paris in french Ppt on cse related topics based Ppt on acid-base titration video Ppt on 3 idiots movie download Ppt on astronomy and astrophysics colleges Ppt on technology development in india Ppt on 2nd world war movies Ppt on solid dielectrics in series Ppt on human nutrition and digestion for kids Ppt on thank you