Question

A new office building in town has x2 + 4 floors. Each floor is 3x2 – 5 feet high. Which expression shows the total height of this office building?
A. 3x4 – 20 feet
B. 3x4 + 7x2 – 20 feet
C.4x2 – 1 feet
D. 4x4 + 6x2 – 20 feet

Answer 1

Answer: OPTION B.

Step-by-step explanation:

You know that:

• $x^{2}+4$ represents the number of floors of the  new office building in town.

• $3x^{2}-5$ represents  the height of each floor in feet.

Therefore, you must multiply $x^{2}+4$ by $3x^{2}-5$ to obtain the expression that shows the total height  in feet of this office building.

Then:

$(x^{2}+4)(3x^{2}-5)=3x^4-5x^2+12x^2-20$

Add the like terms:

$=3x^4+7x^2-20$

Therefore, the answer is the option B.

Answer 2

Answer:

answer : B

Step-by-step explanation: