Which of the following expressions is equal to 2x^2 +8? A. (2x - 4i)(x-2i)
B. (2x-4i)(x+2i)
C. (2x-2i)(x+6i)
D. (2x +4i)(x+2i)

B

Step-by-step explanation:

Expanding the products using FOIL , noting that i² = - 1

A

(2x - 4i)(x - 2i)

= 2x² - 4ix - 4ix + 8i²

= 2x² - 8ix - 8 ≠ 2x² + 8

B

(2x - 4i)(x + 2i)

= 2x² + 4ix - 4ix - 8i²

= 2x² + 8 ← True

C

(2x - 2i)(x + 6i)

= 2x² + 12ix - 2ix - 12i²

= 2x² + 10ix + 12 ≠ 2x² + 8

D

(2x + 4i)(x + 2i)

= 2x² + 4ix + 4ix + 8i²

= 2x² + 8ix - 8 ≠ 2x² + 8

Thus

(2x - 4i)(x + 2i) = 2x² + 8 → B

for ex: the reciprocal of 3/4 is 4/3. it is the opposite.

reciprocal definition:

a mathematical expression or function so related to another that their product is one; the quantity obtained by dividing the number one by a given quantity.

the formula of a slope:

from a table we have

substitute:

the slope of f(x) is -1.

the graph of funcfion g(x) is a horizontal line. the slope of a horizontal line is equal 0. therefore the slope of g(x) is 0.

-1 < 0