Question

Solve the system of equations

3x+5y=30
-5y+3x=15

Answer 1

Explanation:

3x+5y=30

-5x+3y=15

9-(-25)=34

|A|=34

|Ax|= (30×3)-(-15×5)

=90+75

|Ax|= 165

|Ay|=(3×15)-(-5×30)

|Ay|=195

|Ax|= |Ax|÷|A| =165÷34

|Ax|= 4.853

|Ay|= |Ay|÷|A| = 195÷34

|Ay|= 5.735

Answer 2

x = 7.5 y = 1.5

Explanation:

3x + 5y = 30

-5y + 3x = 15

3x + 5y = 30

3x - 5y = 15

6x = 45

x = 45/6

x = 7.5

3(7.5) + 5y = 30

22.5 + 5y = 30

5y = 7.5

y = 7.5/5

y = 1.5

Check:

3(7.5) + 5(1.5) = 30

-5(1.5) + 3(7.5) = 15