How do you simplify #5-[(-3i+4)-2i]#?

1 Answer
Shwetank Mauria
Jun 23, 2016

#5-[(-3i+4)-2i]=1+5i#

Explanation:

#5-[(-3i+4)-2i]#

= #5-[-3i+4-2i]#

= #5-[-5i+4]#

Now we have a negative sign outside brackets.

How do we interpret it?

There are two ways

(i) it is as if we are multiplying by #-1# and hence

#-[-5i+4]=-1xx[-5i+4]#

= #(-1)xx(-5i)+(-1)xx4=5i-4# or

(ii) using simple properties of negative numbers i.e. negative of a negative is positive and negative of a positive is negative and hence again #-{-5i+4]=5i-4#.

In any case, it means we change all the signs inside the brackets and above is equal to

#5+5i-4#

= #1+5i#

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