How do solve the following linear system?: -7x + y = -19 , -2x + 3y = -19 ?

1 Answer
Jan 9, 2016

x=2 and y=-5

Explanation:

For a linear system with 2 different unknowns, we use
Substitution Equation to find the actual value of the unknown.

There are two unknowns, x and y.

Firstly, let -7x+y=-19 as Equation 1
and -2x+3y=-19 as Equation 2.

From one of the equation, for example Equation 1 we can rearrange a new equation and substitute it into the other equation.

Let say, from Equation 1,
-7x+y=-19
Rearrange the equation in terms of only one unknown.
y=-19+7x as Equation 3

Substitute Equation 3 into Equation 2 and we will get;
-2x+3y=-19 given y=-19+7x,

-2x+3(-19+7x)=-19

-2x-57+21x=-19

-2x+21x=-19+57

19x=38

x=2

Substitute x=2 into Equation 3 and we will get;
y=-19+7x given x=2

y=-19+7(2)

y=-5