This is for #1. Not sure about 2 and 3.
Example to help you with 2 and 3:
Solve the following pair of simultaneous linear equations:
Equation 1: 2x + 3y = 8
Equation 2: 3x + 2y = 7
Step 1: Multiply each equation by a suitable number so that the two equations have the same leading coefficient. An easy choice is to multiply Equation 1 by 3, the coefficient of x in Equation 2, and multiply Equation 2 by 2, the x coefficient in Equation 1:
3 * (Eqn 1) --->
3* (2x + 3y = 8)
---> 6x + 9y = 24
2 * (Eqn 2) --->
2 * (3x + 2y = 7)
---> 6x + 4y = 14 Both equations now have the same leading coefficient = 6
Step 2: Subtract the second equation from the first.
-(6x + 9y = 24
-(6x + 4y = 14)
5y = 10
Step 3: Solve this new equation for y.
y = 10/5 = 2
Step 4: Substitute y = 2 into either Equation 1 or Equation 2 above and solve for x. We'll use Equation 1.
2x + 3(2) = 8
2x + 6 = 8 Subtract 6 from both sides
2x = 2 Divide both sides by 2
x = 1
Solution: x = 1, y = 2 or (1,2).
