Question
How to solve the simultaneous equations 3x + y = 17 and y = x + 1 ?
Answers
Dr Russ
There are a few ways to do this. In this case the easiest is probably substituting y in the first equation for x+1
so
3x + (x + 1) =17
remove the brackets
3x + x + 1 = 17
combine the x terms
4x + 1 = 17
move the 1 from the LHS to the RHS
4x +1 -1 = 17 - 1
4x = 16
divide both sides by 4
4x/4 = 16/4
x=4
as
y=x+1
y= 4 + 1
y=5
so
3x + (x + 1) =17
remove the brackets
3x + x + 1 = 17
combine the x terms
4x + 1 = 17
move the 1 from the LHS to the RHS
4x +1 -1 = 17 - 1
4x = 16
divide both sides by 4
4x/4 = 16/4
x=4
as
y=x+1
y= 4 + 1
y=5