Solve for X in the Equation: x + 3 = 7

Q: What if I had x - 3 = 7 instead?

Then you would add 3 to both sides! The goal is always to undo whatever operation is being done to x. Addition undoes subtraction, and subtraction undoes addition.

Q: How do I know which operation cancels out the number?

Use inverse operations:If you see +3, subtract 3If you see -3, add 3If you see ×3, divide by 3If you see ÷3, multiply by 3

Q: Can I check my answer a different way?

Yes! Besides substituting back, you can also think: "What number plus 3 equals 7?" Since 4 + 3 = 7, the answer is definitely x = 4.

Q: What if my answer doesn't work when I substitute it back?

If substitution doesn't work, you made an error somewhere. Start over and carefully check each step. Most mistakes happen when doing arithmetic or forgetting to do the same thing to both sides.

Linear Equations with Single Variable

Solve for X:

$x + 3 = 7$

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Understand the problem

Solve for X:

$x + 3 = 7$

Step-by-step solution

To solve for $x$ , start by isolating $x$ on one side of the equation:
Subtract $3$ from both sides:
$x + 3 - 3 = 7 - 3$ simplifies to
$x = 4$ .

Final Answer

Key Points to Remember

Essential concepts to master this topic

Rule: Isolate the variable by performing the same operation on both sides
Technique: Subtract 3 from both sides: x + 3 - 3 = 7 - 3
Check: Substitute x = 4 back: 4 + 3 = 7 ✓

Common Mistakes

Avoid these frequent errors

Adding instead of subtracting to isolate the variable
Don't add 3 to both sides when you see x + 3 = 7! This gives x + 6 = 10, making the problem harder instead of easier. Always perform the opposite operation to cancel out the number attached to x.

Practice Quiz

Test your knowledge with interactive questions

$$ x+7=14 $$

$x=\text{?}$

FAQ

Everything you need to know about this question

Why do I subtract 3 from both sides instead of just moving it?

In algebra, we don't just "move" numbers across the equals sign. We must maintain balance by doing the same operation to both sides. This keeps the equation true!

What if I had x - 3 = 7 instead?

Then you would add 3 to both sides! The goal is always to undo whatever operation is being done to x. Addition undoes subtraction, and subtraction undoes addition.

How do I know which operation cancels out the number?

Use inverse operations:

If you see +3, subtract 3
If you see -3, add 3
If you see ×3, divide by 3
If you see ÷3, multiply by 3

Can I check my answer a different way?

Yes! Besides substituting back, you can also think: "What number plus 3 equals 7?" Since 4 + 3 = 7, the answer is definitely x = 4.

What if my answer doesn't work when I substitute it back?

If substitution doesn't work, you made an error somewhere. Start over and carefully check each step. Most mistakes happen when doing arithmetic or forgetting to do the same thing to both sides.

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