Question

Which expression is equivalent to (4 + 7i)(3 + 4i)?

Answer 1

28i^2+37i+12

Answer 2

Which expression is equivalent to (4 + 7i)(3 + 4i)?
–16 + 37i
12 – 28i
16 – 37i
37 + 16i

Answer 3

i^2 is -1 so 28i^2 is just -28, so now your equation is 37i-16

Answer 4

Use FOIL or whatever method you use to multiply two binomials.

You get,

12 + 16i + 21i + 28i^2
= 12 + 37i + 28i^2

BUT, i^2 = -1, so you get

12 + 37i + 28(-1)
= 12 + 37i - 28
= -16 + 37i

Answer 5

Yeah me and easyaspi got the same answer so it's probably right.

Answer 6

can anyone help me?

Answer 7

Choice (1) is correct. Most important is to see a step-by-step solution so you can simplify it yourself if there were to be no choices.

Answer 8

Which values of x and y would make the following expression represent a real number?

(4 + 5i)(x + yi)

x = 4, y = 5
x = –4, y = 0
x = 4, y = –5
x = 0, y = 5