(2, -2); {3x + y = 4 x - y = -4?

Question

solve!!!!!!!!!!!!!!!!!!!!!

Answer 1

Substitution Method :

The system of equations are 3x + y = 4 and x - y = 4.

Step 1 : Solve the equation 2 : x - y = 4 for x since the coefficient is 1.

Add y to each side.

x - y + y = 4 + y

x = 4 + y

 

Step 2 : Substitute 4 + y for x in the equation 1 : 3x + y = 4 to find the value of y.

3(4 + y) + y = 4

Apply distributive property : a(b + c) = ab + ac.

3(4) + 3(y) + y = 4

12 + 3y + y = 4

12 + 4y = 4

Subtract 12 from each side.

12 + 4y - 12 = 4 - 12

4y = - 8

Divide each side by 4.

4y/4 = - 8/4

y = - 2.

 

Step 3 : Substitute - 2 for y in either equation to find x.

Equation 2 : x - y = 4

x - (- 2) = 4

x + 2 = 4

Subtract 2 from each side.

x + 2 - 2 = 4 - 2

x = 2.

 

The solution is (2, - 2).