Q. what minus negative one equals four

Q: How do you write the problem as an equation?

The sentence "what minus negative one equals four" is x - (-1) = 4, where x is "what."

Q: How do you solve x - (-1) = 4?

Rewrite x - (-1) as x + 1. So x + 1 = 4. Subtract 1: x = 3.

Q: Why does subtracting a negative become addition?

Because -(-1)=+1: two negatives make a positive. In general a - (-b)=a+b since subtracting the additive inverse of b adds b.

Q: How can I check the solution?

Substitute x=3: 3 - (-1) = 3 + 1 = 4. It matches, so x=3 is correct.

Q: How to show this on a number line?

Subtracting -1 means moving right 1. To land at 4, start at 3 and move right one to reach 4, confirming x=3.

Q: What common sign mistakes should I avoid?

Don’t treat x - (-1) as x - 1. Also avoid dropping a sign when simplifying; always convert x - (-a) to x + a before further steps.

Q: What's a quick generalization?

For any number a, x - (-a) = x + a. To solve x - (-a) = b, rewrite x + a = b and get x = b - a.

Answer

Let \(x\) satisfy \(x-(-1)=4\). Then \(x+1=4\), so \(x=3\).

Detailed Explanation

Problem

Solve the equation: what minus negative one equals four.

Introduce a variable for the unknown.

Let the unknown number be \(x\). Then the sentence “what minus negative one equals four” becomes the equation

\(x – (-1) = 4\).
Use the rule for subtracting a negative number.

Recall that subtracting a negative is the same as adding the positive: for any number \(a\), \(a – (-b) = a + b\). This follows because the additive inverse of \(-b\) is \(b\).

Apply that rule to \(x – (-1)\) to rewrite the left side as an addition:

\(x – (-1) = x + 1\).
Substitute and form a simple linear equation.

Replace the left side in the original equation with the equivalent expression:

\(x + 1 = 4\).
Isolate the variable by performing the inverse operation.

To solve for \(x\), undo the addition of 1 by subtracting 1 from both sides of the equation. Subtraction is the inverse operation of addition, so this preserves equality and isolates \(x\):

\(x + 1 – 1 = 4 – 1\), which simplifies to \(x = 3\).
Check the solution.

Substitute \(x = 3\) back into the original expression to verify:

\(3 – (-1) = 3 + 1 = 4\), which matches the right-hand side.

Answer: \(3\)

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FAQs

How do you write the problem as an equation?

The sentence "what minus negative one equals four" is \(x - (-1) = 4\), where \(x\) is "what."

How do you solve \(x - (-1) = 4\)?

Rewrite \(x - (-1)\) as \(x + 1\). So \(x + 1 = 4\). Subtract 1: \(x = 3\).

Why does subtracting a negative become addition?

Because \(-(-1)=+1\): two negatives make a positive. In general \(a - (-b)=a+b\) since subtracting the additive inverse of \(b\) adds \(b\).

How can I check the solution?

Substitute \(x=3\): \(3 - (-1) = 3 + 1 = 4\). It matches, so \(x=3\) is correct.

How to show this on a number line?

Subtracting \(-1\) means moving right 1. To land at 4, start at 3 and move right one to reach 4, confirming \(x=3\).

What common sign mistakes should I avoid?

Don’t treat \(x - (-1)\) as \(x - 1\). Also avoid dropping a sign when simplifying; always convert \(x - (-a)\) to \(x + a\) before further steps.

What's a quick generalization?

For any number \(a\), \(x - (-a) = x + a\). To solve \(x - (-a) = b\), rewrite \(x + a = b\) and get \(x = b - a\).

How to teach this to beginners?

Use counters or zero-pairs: a negative paired with a positive cancels. Removing a negative (subtracting a debt) adds a positive, e.g., removing \(-1\) gives \(+1\).

What minus negative one equals four?
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