Question

3x+y=115x-y=21 Directions: Solve each system of equations by elimination. Clearly identify your solution.

Answer 1

To solve, we will follow the steps below:

3x+y=11 --------------------------(1)



5x-y=21 ------------------------------(2)

since y have the same coefficient, we can eliminate it directly by adding equation (1) and (2)

adding equation (1) and (2) will result;

8x =32

divide both-side of the equation by 8

x = 4

We move on to eliminate x and then solve for y

To eliminate x, we have to make sure the coefficient of the two equations are the same.

We can achieve this by multiplying through equation (1) by 5 and equation (2) by 3

The result will be;

15x + 5y = 55 ----------------------------(3)

15x - 3y =63 --------------------------------(4)

subtract equation (4) from equation(3)

8y = -8

divide both-side of the equation by 8

y = -1