How do you solve x-y=3 and 7x-y=-3 using substitution?

May 7, 2016

$x = - 1 \mathmr{and} y = - 4$

Explanation:

Another method which will work well in this case is to equate two equal expressions. This is a form of substitution.

Transpose both equations to give $y = \ldots \ldots \ldots . .$

equ 1. $y = x - 3 \text{ and }$ equ 2. $y = 7 x + 3$

Note that $\text{ } y = y$

Therefore: $7 x + 3 = x - 3$
$\text{ } 6 x = - 6$
$\text{ } x = - 1$

Equ 1. $y = - 1 - 3 \Rightarrow y = - 4$