How do you multiply # (-3 + i)(2 + 7i) #?
1 Answer
Nov 20, 2015
You can use FOIL to find:
#(-3+i)(2+7i) = -13-19i#
Explanation:
The FOIL mnemonic helps you to enumerate all the possible combinations of one term from the first binomial and one term from the second when multiplying two binomials.
#(-3+i)(2+7i)#
#= stackrel "First" overbrace ((-3*2)) + stackrel "Outside" overbrace ((-3 * 7i)) + stackrel "Inside" overbrace ((i*2)) + stackrel "Last" overbrace ((i * 7i))#
#=-6-21i+2i+7i^2#
#=-6-21i+2i-7#
#=-13-19i#
