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Example Solution: 2x+3y=20 4x+2y=16
We want to write a system of linear equation that has the ordered pair (1,6) as its solution. To do so, we need to think of two equations that are satisfied by the given point.
? x+? y=? & (I) ? x+? y=? & (II)
Let's choose coefficients of x and y in both equations. Since we want system to have one solution we should not choose the same coefficients for both equations.
2x+3y=? 4x+2y=?
Now, to evaluate right-hand side for each equation we should substitute ( 1, 6) for x and y into the left-hand side and simplify. By doing this, we make sure that each equation is satisfied with the given point.
| Equation 1 | Equation 2 | |
|---|---|---|
| Substitute | 2( 1)+3( 6) | 4( 1)+2( 6) |
| Multiply | 2+18 | 4+12 |
| Add | 20 | 16 |
Finally we can complete our system. Keep in mind that this is just one possible answer for this situation. 2x+3y= 20 4x+2y= 16
(II): LHS-4x=RHS-4x
(II): .LHS /2.=.RHS /2.
(II):Write as a difference of fractions
(II):Calculate quotient
Now we will substitute the right-hand side of Equation 2 for y into Equation 1.
(I): y= 8-2x
(I): Distribute 3
(I):Multiply
(I): Subtract term
(I):LHS-24=RHS-24
(I):.LHS /(-4).=.RHS /(-4).
Finally, we will substitute 1 for x into Equation 2.
(II):x= 1
(II): Identity Property of Multiplication
(II):Subtract term
The solution to our system is (1,6), so we are correct.