Solve This System of Equations: Find x and y in x - y = 5 and 2x - 3y = 8

Question

Solve the following system of equations:

{xy=52x3y=8 \begin{cases} x-y=5 \\ 2x-3y=8 \end{cases}

Video Solution

Solution Steps

00:00 Solve the system of equations
00:05 Multiply the first equation by 2
00:18 Subtract between the equations
00:34 Negative times negative always equals positive
00:40 Collect like terms
00:49 This is the solution for Y
00:54 Isolate X from the first equation
01:02 Substitute the Y value we found and solve for X
01:11 And this is the solution to the problem

Step-by-Step Solution

To solve this system of linear equations using the elimination method, we will follow these steps:

Step 1: Align the equations for elimination.

  • Write the equations as they are given:

xy=5x - y = 5 (Equation 1)

2x3y=82x - 3y = 8 (Equation 2)

Step 2: Eliminate one variable.

  • Multiply Equation 1 by 2 to align the coefficient of xx with that in Equation 2:

2(xy)=2×52(x - y) = 2 \times 5

Thus, the transformed Equation 1 is:

2x2y=102x - 2y = 10 (Equation 3)

  • Subtract Equation 2 from Equation 3 to eliminate xx:

(2x2y)(2x3y)=108(2x - 2y) - (2x - 3y) = 10 - 8

This simplifies to:

y=2y = 2

Step 3: Solve for the other variable.

  • Substitute y=2y = 2 into Equation 1 to solve for xx.

x2=5x - 2 = 5

Solve for xx by adding 2 to both sides:

x=7x = 7

Therefore, the solution to the system of linear equations is x=7\mathbf{x = 7} and y=2\mathbf{y = 2}.

This solution matches the choice:

x=7,y=2x = 7, y = 2

Answer

x=7,y=2 x=7,y=2