Question

How do you solve the system x+2y=4 and 2x−y=8 by substitution?

Answer 1

x + 2y = 4 ------(i)

2x - y = 8 --------(ii)

Solving by SUBSTITUTION:

In the first case let us consider equation (i)

x + 2y = 4

2y = 4 - x

y = (4 - x) / 2

Now, substitute the value of 'y' in " 2x - y = 8 "

2x - (4 - x) / 2 = 8

(4x - 4 + x ) / 2 = 8

(5x - 4 ) / 2 = 8

5x - 4 = 16

5x = 20

x = 4

Put the value of 'x' in equation (i)

(4) + 2y = 4

2y = 0

y = 0

Hence the value of x = 4 and y = 0.

Answer 2

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