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)
7 answers
Use FOIL to multiply them out.
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
(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i-6i
no, 6i^2 is 6*(-1)
so the last term is +6 and the final answer is
7+i
so the last term is +6 and the final answer is
7+i
So did I do any of this correct? What do I need to fix?
You have basically done it correctly, but omitted to change the sign of the last term because i2=-1
(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i +6i
(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i +6i
Oops, it should read:
(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i +6
=7+i
(1-2i)(1+3i)
=1+3i-2i-6i^2
=1+ i-6i^2
= 1+i +6
=7+i
Give me answers of 2.6 of 9 class