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
= No answer!



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 #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 - 6 = 18
x - 6 + 6 = 18 + 6
0 = 24

Correct:
x - 6 = 18
x - 6 + 6 = 18 + 6
x + 0 = 24


Mistake #11:


Incorrect:
6x + 3 / 6x + 2
=  
3 / 2


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



Mistake #12:


Incorrect:
x - 6 = 18
x - 6 + 6 = 18 + 6
0 = 24

Correct:
x - 6 = 18
x - 6 + 6 = 18 + 6
x + 0 = 24


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