Question

How do I solve this equation using the substitution method? They want me to isolate x in the first equation.

x + 3y = -5
4x - y = -33

Answer 1

Explanation:

X+3y= -5

4x-y= -33

1. X=-3y-5 (move the variable to the other side of the equation)

2. 4(-3y-5)-y= -33 (substitute the value of x)

3. -12y-20-y= -33 (cross multiply)

4. -13y-20= -33 (reduce)

5. -13y= -33+20 (isolate variable)

6. -13y= 13 (addition or subtraction)

7. Y= 13÷(-13) (divide)

8. Y= -1

9. X+3(-1)= -5 (substitute value into other equation)

10. X-3= -5 (multiply)

11. X= -5+3 (move to the other side)

12. X= -2 Y= -1