7.4 Solve Linear Systems by Multiplying First Also called Elimination Method Or Linear Combinations Method

Steps to Solve Systems by Elimination Line up the variables Multiply one equation to eliminate a variable Substitute the value into the other equation to solve for the second variable Check to be sure the numbers work in both equations

Solve the system: 𝟐𝒙 −𝒚=𝟑 𝟒𝒙+𝟑𝒚=𝟐𝟏 Lined up – ok Multiply the 1st equation by 3 to eliminate y Use x to find y Check 6x – 3y = 9 4x + 3y = 21 10 x = 30 x = 3 2(3) – y = 3 6 – y = 3 -y = -3 y = 3 4(3) + 3(3) = 21 Solution: (3, 3)

Solve the system: 𝒙+𝟐𝒚=𝟏 𝟓𝒙−𝟒𝒚=−𝟐𝟑 Which variable do you want to eliminate?

Solve the system: 𝟑𝒙+𝟐𝒚=𝟏𝟎 𝟐𝒙+𝟓𝒚=𝟑

Your turn… Solve the system: 𝟑𝒙+𝟓𝒚=𝟐𝟓 𝟐𝒙 −𝟔𝒚=𝟏𝟐

Click on the link: http://www.classzone.com/etest/viewTestPractice.htm?testId=4273

Homework: P 454 #3-29 odd (skip 23) 33, 37, 41