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 :

To solve this problem, let's analyze the information provided about the buildings and their ages:

1. Let [tex]\( x \)[/tex] represent the age of Building C.
2. Building B was built two years before Building C, so Building B's age is [tex]\( x + 2 \)[/tex].
3. Building D was built two years before Building B, making Building D's age [tex]\( x + 4 \)[/tex].

We know from the problem that the product of Building B's age and Building D's age is at least 195. Mathematically, this is expressed as:

[tex]\[
(x + 2)(x + 4) \geq 195
\][/tex]

Now, let's expand this inequality:

1. Multiply the terms:
[tex]\[
(x + 2)(x + 4) = x \cdot x + x \cdot 4 + 2 \cdot x + 2 \cdot 4
\][/tex]
2. Simplify the resulting expression:
[tex]\[
= x^2 + 4x + 2x + 8
\][/tex]
3. Combine like terms:
[tex]\[
= x^2 + 6x + 8
\][/tex]

The inequality then becomes:

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

Therefore, the correct answer is:

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