Answer: OPTION B.
Step-by-step explanation:
You know that:
- [tex]x^{2}+4[/tex] represents the number of floors of the new office building in town.
- [tex]3x^{2}-5[/tex] represents the height of each floor in feet.
Therefore, you must multiply [tex]x^{2}+4[/tex] by [tex]3x^{2}-5[/tex] to obtain the expression that shows the total height in feet of this office building.
Then:
[tex](x^{2}+4)(3x^{2}-5)=3x^4-5x^2+12x^2-20[/tex]
Add the like terms:
[tex]=3x^4+7x^2-20[/tex]
Therefore, the answer is the option B.
