How do you evaluate #-5i \cdot 3i#?

1 Answer
Jim G.
Apr 25, 2018

#"It depends"#

Explanation:

#"this depends on i being an algebraic variable or the"#
#"imaginary number i"#

#"for algebraic variable then"#

#-5ixx3i=(-5xx3)xxixxi=-15i^2#

#"for imaginary number "i=sqrt(-1)#

#"then "i^2=(sqrt(-1))^2=-1#

#rArr-15i^2=-15xx-1=15#

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