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Solve n^3 - 10 = 333

Step by step, with the reason for every step · Solve x² = 49 and x³ = 27 · Foundations

Step by step

The question

Question: solve n³ − 10 = 333.

n3 − 10 = 333

n³ means n times n times n.

We want just n.

n³ = n × n × n

1 Remove the − 10

We want n³ by itself.

The − 10 is in the way.

To remove − 10, we add 10.

We do it on both sides, so they stay equal.

n3 − 10 + 10 = 333 + 10

− 10 and + 10 make zero.

Cross them out.

Now we have n³ = 343.

n3 = 343

2 Cube root of both sides

The cube root asks: which number, times itself three times, makes this?

∛27 = ? → ? × ? × ? = 27

The cubes: 1 times 1 times 1 is 1.

2 times 2 times 2 is 8.

3 times 3 times 3 is 27.

4 times 4 times 4 is 64.

5 times 5 times 5 is 125.

6 times 6 times 6 is 216.

1³ = 1, 2³ = 8, 3³ = 27, 4³ = 64, 5³ = 125, 6³ = 216

n is the cube root of 343.

n = 3√343

7 times 7 times 7 is 343.

So n = 7.

n = 7

Careful!

A cube has one answer, not two.

Minus 7, cubed, is minus 343.

Not like x² = 49.

Careful: not n = 7 or n = −7 ✗

3 Check

Let's check: 7 times 7 times 7 is 343.

7 × 7 × 7 = 343

Minus 10 is 333.

The same as the right side.

So the answer is right!

343 − 10 = 333

Let's look back.

First: remove the − 10.

Then: cube root of both sides.

Last: check.

Answer
Careful: not n = 7 or n = −7 ✗

Your turn

Try this one yourself, then check:

Solve n3 − 3 = 24
Show the answer
n = 3

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