High School

Select the correct answer.

A construction company is analyzing which of its older projects need renovation. Building B was built two years before Building C. Building D was built two years before Building B. The product of Building B's age and Building D's age is at least 195. If [tex]x[/tex] represents the age of Building C, which inequality represents this situation?

A. [tex]x^2 + 8x + 16 \geq 195[/tex]

B. [tex]x^2 + 6x + 8 \geq 195[/tex]

C. [tex]x^2 + 4 \geq 195[/tex]

D. [tex]x^2 + 4x + 4 \geq 195[/tex]

Answer :

Let's solve the problem step-by-step.

We need to find the appropriate inequality to represent the ages of the buildings:

1. Define the variables:
- Let [tex]\( x \)[/tex] be the age of building C.

2. Determine the ages of the other buildings:
- Building B was built 2 years before building C, so the age of building B is [tex]\( x - 2 \)[/tex].
- Building D was built 2 years before building B, so the age of building D is [tex]\( x - 4 \)[/tex].

3. Formulate the inequality:
- We're given that the product of building B's age and building D's age should be at least 195. Therefore, we write:
[tex]\[
(x - 2)(x - 4) \geq 195
\][/tex]

4. Simplify the expression:
- Expand the expression:
[tex]\[
(x - 2)(x - 4) = x^2 - 4x - 2x + 8 = x^2 - 6x + 8
\][/tex]

5. Set up the inequality:
- The inequality becomes:
[tex]\[
x^2 - 6x + 8 \geq 195
\][/tex]

6. Match with the given options:
- The inequality [tex]\( x^2 - 6x + 8 \geq 195 \)[/tex] corresponds to option B.

Therefore, the correct answer is:

B. [tex]\( x^2 - 6x + 8 \geq 195 \)[/tex]