Asked by Breanna

Simplify: Write answers in the form of a + bi, where a and b are real numbers.

a. (1-2i)(1+3i)

b. (3-5i)(8-2i)
Answered by bobpursley
Use FOIL to multiply them out.
Answered by Breanna
IS this correct, i notice that i^2 = -1 what does this mean?

(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i-6i
Answered by bobpursley
no, 6i^2 is 6*(-1)
so the last term is +6 and the final answer is
7+i
Answered by Breanna
So did I do any of this correct? What do I need to fix?
Answered by MathMate
You have basically done it correctly, but omitted to change the sign of the last term because i<sup>2</sup>=-1

(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i <b>+</b>6i
Answered by MathMate
Oops, it should read:

(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i <b>+</b>6
=<b>7+i</b>
Answered by Mnahil
Give me answers of 2.6 of 9 class
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