Solve the System of Linear Equations: 6x - 2y = 24 and x + 5y = 4

Linear Equations with Elimination Method

6x2y=24 6x-2y=24

x+5y=4 x+5y=4

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:00 Solve
00:04 Let's multiply one of the equations by 6, so we can subtract between them
00:14 Now let's subtract between the equations
00:19 Let's reduce what we can
00:29 Let's group terms
00:34 Let's isolate Y
00:39 This is the value of Y
00:44 Now let's substitute Y to find the value of X
00:51 And this is the solution to the question

Step-by-step written solution

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1

Understand the problem

6x2y=24 6x-2y=24

x+5y=4 x+5y=4

2

Step-by-step solution

To solve this problem, we'll begin with the system of equations:

6x2y=24(Equation 1)x+5y=4(Equation 2) \begin{aligned} & 6x - 2y = 24 \quad \text{(Equation 1)} \\ & x + 5y = 4 \quad \text{(Equation 2)} \end{aligned}

We will use the elimination method to solve for x x and y y . First, let's align the equations to eliminate y y .

We notice that if we multiply Equation 2 by 2, it becomes easier to align coefficients with Equation 1:

2(x+5y)=2×4 2(x + 5y) = 2 \times 4

Simplifying gives:

2x+10y=8(Equation 3) 2x + 10y = 8 \quad \text{(Equation 3)}

Now, we have:

6x2y=242x+10y=8 \begin{aligned} & 6x - 2y = 24 \\ & 2x + 10y = 8 \\ \end{aligned}

To eliminate y y , let's add the equations after aligning coefficients. Multiply Equation 1 by 5 and Equation 3 by 1 to eliminate y y :

5(6x2y)=5(24)1(2x+10y)=1(8) \begin{aligned} 5(6x - 2y) &= 5(24) \\ 1(2x + 10y) &= 1(8) \\ \end{aligned}

Which gives:

30x10y=1202x+10y=8 \begin{aligned} 30x - 10y &= 120 \\ 2x + 10y &= 8 \end{aligned}

Adding these:

(30x10y)+(2x+10y)=120+8 (30x - 10y) + (2x + 10y) = 120 + 8

32x=128 32x = 128

Solving for x x , we divide by 32:

x=12832=4 x = \frac{128}{32} = 4

Substitute x=4 x = 4 back into Equation 2:

4+5y=4 4 + 5y = 4

Subtract 4 on both sides:

5y=0 5y = 0

Dividing by 5 gives:

y=0 y = 0

Thus, we have determined the solution to the system of equations:

x=4,y=0 x = 4, y = 0 .

3

Final Answer

x=4,y=0 x=4,y=0

Key Points to Remember

Essential concepts to master this topic
  • System Setup: Align equations to eliminate one variable completely
  • Technique: Multiply equations by coefficients: 5(6x - 2y) = 5(24)
  • Check: Substitute x = 4, y = 0: 6(4) - 2(0) = 24 ✓

Common Mistakes

Avoid these frequent errors
  • Forgetting to multiply entire equations by coefficients
    Don't multiply just one term like 6x by 5 and leave -2y unchanged = unbalanced equation! This breaks the equality and leads to wrong solutions. Always multiply every single term on both sides by the same coefficient.

Practice Quiz

Test your knowledge with interactive questions

\( \begin{cases} x+y=8 \\ x-y=6 \end{cases} \)

FAQ

Everything you need to know about this question

Why multiply equation 1 by 5 and equation 3 by 1?

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We need the y-coefficients to be opposites so they cancel out! Equation 1 has -2y, and equation 3 has +10y. Multiplying by 5 gives us -10y and +10y, which add to zero.

Can I solve this using substitution instead?

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Absolutely! You could solve x+5y=4 x + 5y = 4 for x, getting x=45y x = 4 - 5y , then substitute into the first equation. Both methods work!

What if I get different coefficients after multiplying?

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That's normal! The goal is to make one variable's coefficients opposite numbers (like +10y and -10y) so they cancel when you add the equations together.

How do I know which variable to eliminate first?

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Look for the variable that's easier to eliminate! In this problem, y has coefficients -2 and +5, which are simpler to work with than the x coefficients 6 and 1.

Why does x = 4, y = 0 work for both equations?

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Let's check! First equation: 6(4)2(0)=240=24 6(4) - 2(0) = 24 - 0 = 24 ✓
Second equation: 4+5(0)=4+0=4 4 + 5(0) = 4 + 0 = 4 ✓
Both sides match!

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