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Mr. Sims Algebra 2 Section 10.2 B Substitution Method Solve using the substitution method. 1. 2x + y = 5 -2x -2x y = -2x + 5 substitute into other equation for y solve one equation for one variable get one to read x = or y = 4x + 3y = 7 4x + 3(-2x + 5) = 7 4x – 6x + 15 = 7 -2x + 15 = 7 solve for x distributive property combine like terms -15 -15 -2x = -8 x=4 substitute into equation that reads y = y = -2x + 5 y = -2(4) + 5 y = -8 + 5 y = -3 Mr. Sims 2. 4x + 2y = 2 solve one equation for one variable get one to read x = or y = x + 3y = 13 -3y -3y x = -3y + 13 substitute into other equation for x 4(-3y + 13) + 2y = 2 -12y + 52 + 2y = 2 -10y + 52 = 2 solve for y distributive property combine like terms -52 -52 -10y = -50 y=5 x = -3y + 13 x = -3(5) + 13 x = -15 + 13 x = -2 substitute into equation that reads x = Mr. Sims 3. 6x – 2y = - 4 get one equation to read x = or y = -8x + y = -3 +8x +8x y = 8x - 3 substitute into other equation for y 6x – 2(8x – 3) = - 4 solve for x 6x – 16x + 6 = - 4 -10x + 6 = - 4 -6 distributive property -6 -10x = -10 x=1 substitute into equation that reads y = y = 8x - 3 y = 8(1) – 3 y=8–3 y=5 Mr. Sims 4. x – 3y = 18 x = 3y + 18 substitute into other equation for x +3y +3y get one equation to -x + 3y = 12 read x = or y = -(3y + 18) + 3y = 12 -3y – 18 + 3y = 12 -18 = 12 solve for y distributive property combine like terms since –18 = 12 is never true, there is no solution Mr. Sims 5. 2x 5y 1 get one equation to read x = or y = 5 1 x y 2 2 -5/2y -5/2y 5 1 x y 2 2 substitute into other equation for x 1 5 2 y 5y 1 2 2 -5y + 1 + 5y = 1 1=1 distributive property combine like terms since 1 =1 is always true, there are infinitely many solutions Mr. Sims 6. x – 3y = 8 +3y +3y x = 3y + 8 substitute into other equation for x get one equation to read x = or y = -2x + 3y = -7 -2(3y + 8) + 3y = -7 solve for y -6y – 16 + 3y = -7 distributive property -3y – 16 = -7 combine like terms +16 +16 -3y = 9 y = -3 substitute into equation that reads x = x = 3y + 8 x = 3(-3) + 8 x = -9 + 8 x = -1 Mr. Sims Solve using the substitution method. Algebra 2 Section 10.2 B Substitution Method 1.) 2x – 5y = 9 -3x + y = -7 2.) -3x + 4y = 1 x – 2y = 1 3.) 6x + 2y = 11 4x + y = 6 4.) x – 2y = -1 5x – 7y = 4 5.) 4x + 3y = 3 2x + y = -3 6.) 10x – 16y = 17 x+y=3 Mr. Sims Any rebroadcast, reproduction, or other use of the pictures and materials from this site and presentations, without the express written consent of Mr. Sims, is prohibited. © Mr. Sims. All rights reserved. Mr. Sims