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how do i solve by substitution?

+1 vote
My book is asking me to solve by substitution and i have no idea how to do this.
29.3x-2y=4, x=2
31.y=2x-1, x=2y=3
asked Mar 1, 2013 in ALGEBRA 2 by andrew Scholar

3 Answers

+1 vote
29.
3x-2y=4
substitute x=2 in 3x-2y=4
3 * 2 - 2y = 4
6 - 2y = 4
subtract 6 from each side
-2y = -2
divide each side by -2
y=1
(x, y) = (2, 1)

31.
Substitute y=2x-1 in x+2y=3
x +2 * (2x - 1) = 3
x + 4x - 2 = 3
5x - 2 = 3
add 2 to each side
5x = 5
divide each side by 5
x = 1
substitute x = 1 in y=2x-1
y = 2 * 1 - 1 = 1
(x, y) = (1, 1)
answered Mar 1, 2013 by steve Scholar
+1 vote
29.

substitute x=2
3 * 2 - 2y = 4
6 - 2y = 4    (subtract 6 from each side)
-2y = -2       (divide each side by -2)
y=1
(x, y) = (2, 1)
Solution to the system of equation 3x-2y=4, x=2 is (2, 1).

31.

Substitute y=2x-1
x +2 * (2x - 1) = 3
x + 4x - 2 = 3  (Distribute 2)
5x - 2 = 3       (add 2 to each side)
5x = 5             (divide each side by 5)
x = 1
substitute x = 1 in y=2x-1
y = 2 * 1 - 1 = 1
(x, y) = (1, 1)

Solution to the system of equation 3x-2y=4, x=2 is (1, 1).
answered Mar 3, 2013 by casacop Expert
edited Mar 3, 2013 by casacop
+1 vote
Solution to the system of equation 3x-2y=4, x=2 is (2, 1).

Solution to the system of equation 3x-2y=4, x=2 is (1, 1).
answered Mar 5, 2013 by Naren Answers Apprentice

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