Question

System of equations by substitution
how do this?
y= x+2
y= -4x+7

Answer 1

Equations are given,
y= x+2

y= -4x+7

As you can see both the expressions, x+2 and -4x+7 are equal to "y". That means they are equal to each other too.

So let's equal them and solve it.


`x+2=-4x+7\\ \\ x+2+4x=7\\ \\ x+4x+2=7\\ \\ 5x+2=7\\ \\ 5x=7-2\\ \\ 5x=5\\ \\ x=\frac { 5 }{ 5 } \\ \\ x=1`

Now we have x's value we will plug it in the first equation to find "y".


`x=1\\ \\ y=x+2\\ \\ y=1+2\\ \\ y=3`

(1,3)