Which expression has an equivalent value to [tex]$x^2 + 9x + 8$[/tex] for all values of [tex]x[/tex]?

A. [tex](x + 1)(x + 8)[/tex]
B. [tex](x + 2)(x + 6)[/tex]
C. [tex](x + 4)(x + 4)[/tex]
D. [tex](x + 5)(x + 4)[/tex]



Answer :

To determine which given expression is equivalent to [tex]\( x^2 + 9x + 8 \)[/tex] for all values of [tex]\( x \)[/tex], we need to expand each expression and compare it to [tex]\( x^2 + 9x + 8 \)[/tex].

Let's begin with each option:

1. Option [tex]\((x+1)(x+8)\)[/tex]:
[tex]\[ (x+1)(x+8) = x \cdot x + x \cdot 8 + 1 \cdot x + 1 \cdot 8 = x^2 + 8x + x + 8 = x^2 + 9x + 8 \][/tex]
The expanded form is [tex]\( x^2 + 9x + 8 \)[/tex].

2. Option [tex]\((x+2)(x+6)\)[/tex]:
[tex]\[ (x+2)(x+6) = x \cdot x + x \cdot 6 + 2 \cdot x + 2 \cdot 6 = x^2 + 6x + 2x + 12 = x^2 + 8x + 12 \][/tex]
The expanded form is [tex]\( x^2 + 8x + 12 \)[/tex].

3. Option [tex]\((x+4)(x+4)\)[/tex]:
[tex]\[ (x+4)(x+4) = x \cdot x + x \cdot 4 + 4 \cdot x + 4 \cdot 4 = x^2 + 4x + 4x + 16 = x^2 + 8x + 16 \][/tex]
The expanded form is [tex]\( x^2 + 8x + 16 \)[/tex].

4. Option [tex]\((x+5)(x+4)\)[/tex]:
[tex]\[ (x+5)(x+4) = x \cdot x + x \cdot 4 + 5 \cdot x + 5 \cdot 4 = x^2 + 4x + 5x + 20 = x^2 + 9x + 20 \][/tex]
The expanded form is [tex]\( x^2 + 9x + 20 \)[/tex].

Now we compare each expanded form to [tex]\( x^2 + 9x + 8 \)[/tex]:

- Option [tex]\((x+1)(x+8)\)[/tex] expands to [tex]\( x^2 + 9x + 8 \)[/tex], which matches exactly.
- Option [tex]\((x+2)(x+6)\)[/tex] expands to [tex]\( x^2 + 8x + 12 \)[/tex], which does not match.
- Option [tex]\((x+4)(x+4)\)[/tex] expands to [tex]\( x^2 + 8x + 16 \)[/tex], which does not match.
- Option [tex]\((x+5)(x+4)\)[/tex] expands to [tex]\( x^2 + 9x + 20 \)[/tex], which does not match.

Thus, the expression that is equivalent to [tex]\( x^2 + 9x + 8 \)[/tex] for all values of [tex]\( x \)[/tex] is:
[tex]\[ (x+1)(x+8) \][/tex]