How do you solve 2x+y=5 and y=3x+2 using substitution?

2 Answers
Jul 30, 2016

x=35
y=195

Explanation:

2x+y=5
Putting y=3x+2 in the above equation we get
2x+3x+2=5
or
5x+2=5
or
5x=52
or
5x=3
or
x=35=======Ans 1
By putting x=35 in the equation y=3x+2
we get
y=3(35)+2
or
y=95+2
or
y=9+2(5)5
or
y=9+105
or
y=195=====Ans 2

Jul 30, 2016

x=35,y=345

Explanation:

This type of question is particularly common when working with straight lines.

Note that there is a single y term in both equations.

y=2x+5 and y=3x+2

At the point where the two lines intersect, the xandy values are equal.

If y = y it follows that:

3x+2=2x+5

5x=3

x=35

There are now two equations to find a value for y. If we get the same answer for each we will know our answers are correct.

y=3×35+2=345 y=2×35+5=345