1. x = 6, y = -3 2. x = 0, y = -2 3. x = 5, y = 4 6. x = -4, y = -8 5. x = -5, y = -4 6. x = -2 y = 4
How do we solve the system of equations using substitution?
To Solve the system of equation by substitution, qw say
A. 3x+2y =12
y=x−9
Substitute y = x−9 into the first equation:
3x + 2(x-9) = 12; 3x +2x - 18 = 12
5x = 12 + 18; 5x = 30 ⇒ x = 30/5 = 6
y = 6−9 = -3
B. 4x + y =-2
y = 2x - 2
4x + 2x - 2 = -2
6x = -2 + 2 → 6x = 0 ⇒ x = 0
y = 2(0) - 2 ⇒ y = -2
C. -3x + 5y = 5
y = x - 1
-3x + 5(x - 1) = 5
-3x + 5x -5 = 5; 2x = 5+5
x = 10/2 = 5
y = 5 - 1 ⇒ y = 4
D. 2x + y = -16
y = 2x
2x + 2x = -16
4x = -16 ⇒ x = -4
y = 2(-4) ⇒ y = -8
E. 7x = -35
-8x + 9y = 4
7x = -35 ⇒ x = -5
-8(-5) + 9y = 4
40 + 9y = 4
9y = -36
y = -4
F. -4x + 3y = 20
-14y = -56
y = -56/-14 ⇒ y = 4
-4x + 3(4) = 20
-4x = 20 -12
-4x = 8 ⇒ x = -2