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3 votes
HELP ASAP PLEASE!
Evaluate the numerical expression.

− 1/3 − (− 4/9 )

2 Answers

1 vote
I use KCC (Keep Change Change) so -1/3 would be kept the same, the minus would be turned positive and the -4/9 would be changed to positive 4/9.
Then it will look like this: -1/3+(+4/9) = 1/9
Hope this helps.
User Mhadidg
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5 votes
I gotcha covered.

So, let's separate the problem to its individual components.

We have -1/3

and we're subtracting (-)

- 4/9

Now, we can see that we have two minus signs right next to each other.

If that occurs, we can change the two minus signs to one positive sign. It's just a rule in math.

So, we can rewrite the problem:

-1/3 - (- 4/9) can be rewritten to:

-1/3 + 4/9

But!!! We're not finished yet. The denominators (that means bottom part of a fraction) are not the same.

The denominators most of the time have to be same.

We have a 3 and a 9...

How do we make them the same? I gotcha covered again.

There's the criss-cross method, also known as cross multiplication, but I won't go over that because there's an easier way for this problem.

Here's the easier way:

3 * ? = 9

? = 3

So, 3 * 3 = 9.

We can multiply the - 1/3 by 3 to get the common denominator of 9.

There's a rule for this too... what we multiply by the denominator, we also MUST multiply that same number to the numerator (the top part of a fraction).

So, - 1/3 * (3/3) = - 3/9.

We can then add the fractions together since they have the same denominator.

Here it is:

- 3/9 + 4/9

Since - 3/9 is negative, we subtract that from 4/9...

Rewritten, we have:

4/9 - 3/9 = 1/9.

The denominators don't get changed unless we multiply or divide, so we only do the math for the numerators.

1/9 is the answer.

Good luck, and if you have more questions then please leave a comment!



User Carlo Corradini
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7.1k points