Question

Solve these systems using substitution

8) y = -3x + 5
3x + 2 y = 1


10) x + 3y = 8
3x + 3y = 12

Answer 1

8)Answer x=3, y=-4

10)Answer x=2, y=2

Explanation:

8) y = -3x + 5 (1)

3x + 2 y = 1 2y=-3x+1 (2)

substitute (1) into (2) for y: 2[(-3x)+5]=-3x+1

-6x+10=-3x+1

-6x+3x=1-10

-3x=-9

x=-9/-3, x=3

plug x=3 into (1) y=-3(3)+5, y=-4

Answer (3,-4)

10) x + 3y = 8  x=-3y+8 (1)

3x + 3y = 12 3x= -3y+12 (2)

Substitute (1) into (2) for x: 3[(-3y)+8]=-3y+12

-9y+24=-3y+12

-9y+3y=12-24

-6y =-12

y=-12/-6

y=2

Plug y=2 in (1) x=-3y+8, x =-3(2)+8, x = 2

Answer (2,2)