Lesson 1
Example 1. Use either elimination or the substitution method to solve each system of equations. 3x -2y = 7 & 2x +5y = 9 A. Using substitution method 3x -2y = 7 ( 1 st eq.) 2x +5y = 9 ( 2 nd eq.)
1. Choose an equation to change either in y form or x form. For example, I choose eq. 1 & change it to x form. 3x -2y = 7 ( 1 st eq.) 3x = 2y + 7 x = 3 rd equation
2. Substitute the value of x in the 2 nd equation. 2( ) +5y = 9 ( 2 nd eq.) Use distributive property Multiply both sides by 3 4y y = 27
Multiply both sides by 3 4y y = 27 by simplifying, 19y = 13 using division, y =
3. Find x by substituting the value of y in the 1 st equation or 3 rd eq. 3 rd equation By simplifying Get the LCD & simplify
Example 1. Use either elimination or the substitution method to solve each system of equations. 3x -2y = 7 ( 1 st eq.) 2x +5y = 9 ( 2 nd eq.) The solution set is
A. Using elimination method 3x -2y = 7 ( 1 st eq.) 2x +5y = 9 ( 2 nd eq.)
1. Choose a variable to eliminate. For example, I choose x. 3x -2y = 7 ( 1 st eq.) 2x +5y = 9 ( 2 nd eq.) To eliminate x, multiply the 1 st eq. by -2 and multiply the 2 nd eq. by 3. then add the 1 st eq. to the 2 nd eq.. -2(3x -2y = 7) ( 1 st eq.) 3(2x +5y = 9) ( 2 nd eq.)
-6x + 4y = -14 + 6x +15y = 27 19y = 13 y = 13 19 2. Now substitute the value of y in either equation to find the value of x.
I choose the 2 nd equation. 2x +5y = 9) ( 2 nd eq.) Multiply both sides by 19 38 x + 65 = 171 38x = (subtract both sides by 65)
38 x = 106 (by subtraction prop.) X = 106 (by division prop.) 38 X = 53 (by simplifying) 19