Common mistakes in math

Find here a list of common mistakes in math made by students on a regular basis. Check the list and avoid making them yourself

Mistake #1:

Incorrect: 43 = 4 × 3

Correct: 43 = 4 × 4 × 4

Mistake #2:

Incorrect: -32 = -3 × -3 = 9

Correct: -(3 × 3) = -9

Mistake #3:

Incorrect:
8 / 0
= 0

Correct:
8 / 0

Mistake #4:

Incorrect: -5 + 15 = -20

Correct: -5 + 15 = 10

Mistake #5:

 Incorrect: √9 + 16 = √9 + √16 = 3 + 4 = 7

 Correct: √9 + 16 = √25 = 5

Mistake #5:

 Incorrect: √9 + 16 = √9 + √16 = 3 + 4 = 7

 Correct: √9 + 16 = √25 = 5

Mistake #6:

Incorrect:
x + 8 > 10
x + 8 - 8 < 10 - 8
x = 2

Correct:
x + 8 > 10
x + 8 - 8 > 10 - 8
x > 2

Mistake #7:

Incorrect: y3 × y2 = y6

Correct: y3 × y2 = y5

Mistake #8:

Incorrect: (2y)4 = 2y4

Correct: (2y)4 = 16y4

Mistake #9:

Incorrect: 4 × (2z + 5) = 4 × 2z + 5

Correct: 4 × (2z + 5) = 4 × 2z + 4 × 5

Mistake #10:

Incorrect:
x + 10 = 20
x + 10 - 10 = 20 - 10
0 = 10

Correct:
x + 10 = 20
x + 10 - 10 = 20 - 10
x + 0 = 10

Mistake #11:

 Incorrect: 6x + 3 / 6x + 2 = 3 / 2

 Correct: 6x + 3 / 6x + 2 = 6x + 3 / 6x + 2

Mistake #12:

Incorrect:
x + 10 = 20
x + 10 - 10 = 20 - 10
0 = 10

Correct:
x + 10 = 20
x + 10 - 10 = 20 - 10
x + 0 = 10

Mistake #11:

 Incorrect: 6x + 3 / 6x + 2 = 3 / 2

 Correct: 6x + 3 / 6x + 2 = 6x + 3 / 6x + 2

Mistake #12:

Incorrect:
x + 10 = 20
x + 10 - 10 = 20 - 10
0 = 10

Correct:
x + 10 = 20
x + 10 - 10 = 20 - 10
x + 0 = 10

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