Question

How do you simplify $-3+9-12$ ?

Answer 1

Hint: To simplify the given algebraic expression i.e. $-3+9-12$ we are going to first collect the like sign numbers together. Then we will take the negative sign out from the terms which have negative signs and inside the bracket add these terms. Then we will subtract the term with a negative sign with the term with positive sign.

Complete step by step answer:
The algebraic expression given in the above problem which we are asked to simplify is as follows:
$-3+9-12$
Now, we are going to write the terms together which are having the same sign so writing the terms -3 and -12 together and the remaining term +9 after those two terms we get,
$\Rightarrow -3-12+9$
Taking negative sign as common from the first two terms of the above expression we get,
$\Rightarrow -\left( 3+12 \right)+9$
Now, we are going to add the terms written inside the bracket of the above expression we get,
$\Rightarrow -\left( 15 \right)+9$
Rewriting the above expression by writing addition term first followed by negative term we get,
$\Rightarrow 9-15$
Now, we are going to subtract 9 from 15 we get 6 but with a negative sign because the greater number is with negative sign so the above expression will resolve to:
-6

Hence, the simplification of the given algebraic expression is -6.

Note: The plausible mistake that could be possible in the above problem is that you might forget to write a negative sign in the final answer. The reason being because we are in the habit of writing the subtraction with a negative sign but in the above subtraction in the last step of the above solution, larger number 15 is written with a negative sign so the final answer is written with a negative sign.