Math 10 – Week 15

Something I learned this week is how to find the intercept of two lines. There are two methods to this, but I’m only going to explain the substitution method.

There are two lines, so there are two equations. If you take one of the equations and isolate one of the variables, you can insert your one equation into the other.

Ex.

x+4y=-3,   3x-7y=29

4y+3=x,   3(4y+3)-7y=29

Once you insert your equation into the other, solve the equation so that it looks like (single variable = number).

12y+9-7y=29

12y-7y=29-9

2/(5y=20)

y=10

Once you solve whatever variable you were solving, insert your variable into any question to solve the other variable.

x+4(10)=-3

x+40=-3

x=-43

(-43, 10)