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How do you simplify #-4(-3i)(-5+7i)#?

Answer 1

Caleb Alexander

#-84-60i#

#-4(-3i)=12i#

#rArr12i(-5+7i)=-60i+84i^2#

#color(orange)"Reminder" color(red)(|bar(ul(color(white)(a/a)color(black)(i^2=(sqrt(-1))^2=-1)color(white)(a/a)|)))#

#rArr-60i+84i^2=-60i-84#

#rArr-4(-3i)(-5+7i)=-84-60i#

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Answer 2

Lincoln Anderson

To simplify (-4(-3i)(-5+7i)), first distribute the (-4) across the terms inside the parentheses:

[ (-4)(-3i)(-5) + (-4)(-3i)(7i) ]

[ 12i(-5) + (-12i)(7i) ]

[ -60i + 84i^2 ]

Next, substitute (i^2 = -1):

[ -60i + 84(-1) ]

[ -60i - 84 ]

Thus, the simplified expression is (-60i - 84).

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.