PSAT Math : How to subtract negative numbers

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #1 : How To Subtract Negative Numbers

If x is a negative integer, what else must be a negative integer?

 

Possible Answers:

x – (–x)

x² – x

x – x

Correct answer:

x – (–x)

Explanation:

By choosing a random negative number, for example: –4, we can input the number into each choice and see if we come out with another negative number.  When we put –4 in for x, we would have –4 – (–(–4)) or –4 – 4, which is –8.  Plugging in the other options gives a positive answer.  You can try other negative numbers, if needed, to confirm this still works. 

 

 

Example Question #2 : Negative Numbers

–7 – 7= x

–7 – (–7) = y

what are x and y, respectively

Possible Answers:

x = 14, y = –14

x = –14, y = 14

y = 0, x = 14

x = 0, y = 0

x = –14, y = 0

Correct answer:

x = –14, y = 0

Explanation:

x: –7 – 7= –7 + –7 = –14

y: –7 – (–7) = –7 + 7 = 0

when subtracting a negative number, turn it into an addition problem

Example Question #1 : How To Subtract Negative Numbers

Possible Answers:

15

2

13

16

5

Correct answer:

16

Explanation:

Subtracting a negative number is just like adding its absolute value.

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