Question

Solve the following system of equations. Please show your work to receive full credit.
x - y = 10
2x + y = 2

Part 2:
Explain which method you chose to solve the system and why you felt it was the best choice.

Answer 1

I would just add the 2 functions together and the y's would cancel out. Then solve for x plug that back into one of the equations to get y.

Answer 2

x - y = 10 ---------(i)
2x + y = 2 ---------(ii)

rearranging (i) we get x = 10 + y
substitute in (ii)
2(10 + y) + y = 2
20 + 2y + y = 2
3y = 2 - 20
y = - 18/3
y = -6
substitute in (i)
x - (-6) = 10
x + 6 = 10
x = 10 - 6
x = 4

so solution is (4, -6)

(ii) we used the substitution method because it was easy to get x in terms of y from (i) by a simple rearrangement of terms