Question 729791
If possible solve the system of equations. Use any method. If there is not a unique solution state a reason why
3x - 9y = 3
-15x + 45y = -15
thanks!!


The above system of equation can be
solved by substitution.

3x - 9y = 3 (Equation 1)

-15x + 45y = -15 (Equation 2)


We first take Equation 1

3x - 9y = 3

Add 9y to each side of the equation.

3x - 9y + 9y = 3 + 9y

3x = 3 + 9y

Divide each item above by 3:

x = 1 + 3y (Equation 3)


Substitute Equation 3 into Equation 2.


-15x + 45y = -15 (Equation 2)

-15(1 + 3y) + 45y = -15

-15 - 45y + 45y = -15

Combine like terms:

-45y + 45y = 0

Therefore:

-15 = -15

Divide each side by -15

x = 1



Substitute x = 1 into Equation 1


3x - 9y = 3

3(1) - 9y = 3

3 - 9y = 3

Add 9y to each side of the equation.

3 - 9y + 9y = 3 + 9y

3 = 3 + 9y

Subtract 3 from each side of the equation.

3 - 3 = 3 + 9y - 3

0 = 9y or

9y = 0

Therefore:

y = 0



Answer:

x = 1 and

y = 0






Lennox Obuong
Algebra Tutor
Nairobi, Kenya