Question

(7-7i) (7+2i)

Answer 1

Use FOIL

Answer 2

i*i=-1

7*7=49
-7i*2i=14
7*-7i=-49i
7*2i=14i

Add all terms together

Answer 3

ok thanks

Answer 4

do you fully understand how i did that?

Answer 5

i understand how you did it until the 7 * -7 step

Answer 6

that was not a step ^ ?

Answer 7

okay so you have
(7-7i)(7+2i)

(a-bi)(c+di) = ac + bd - (cb)i + (ad)i

so you understand the first two steps then:
7*-7i=-49i
7*2i=14i

basically in order to get rid of the 'i' you have to multiply it by another 'i'
but in these two steps, an 'i' only appears one of the terms so it has to stay there
so you should multiply the numbers and leave the 'i' where it is

does that make sense?

Answer 8

(7-7i) (7+2i)

7*7 = 49
7*2i = 14i

-7i*7 = -49i
-7i*2i = -14i^2

so:
49 + 14i - 49i - 14i^2

remember: \(i^2 = -1\)

then:
49 - 35i - 14(-1)

so:
49 - 35i + 14

then:
63 - 35i

standard form: a + bi

Answer 9

thanks both of you they both are easier to understand

Answer 10

no prob