Solving system with elimination part 2

Solving system with elimination part 2

Sometimes you must multiply both equations in order to eliminate something.

Example 1

3x – 2y = 2

5x – 5y = 10

With this system there is nothing that can be eliminated by just multiplying on3 equation. That means the first thing we have to decide is what we want to get rid of. Lets say we want to get rid of y.

The coefficients of y are -2 and -5.

10 is the smallest number and is called the least common multiple.

• We find this number so we can know how to change the coefficients so they will add to zero.

• 3x – 2y = 2

  5x – 5y = 10

• We will need to use multiplication to get a 10 and a -10y so when we add them we will eliminate y.

Open Ended

Why do we need it to be +10y instead of -10y?