Consider the expressions shown below.

\begin{tabular}{|c|c|c|}
\hline A & B & C \\
\hline [tex]$-9x^2 - 2x + 7$[/tex] & [tex]$9x^2 - 2x + 2$[/tex] & [tex]$9x^2 + 2x - 7$[/tex] \\
\hline
\end{tabular}

Complete the following statements with the letter that represents the expression.

1. [tex]$\left(7x^2 - 5x + 3\right) + \left(2x^2 + 3x - 1\right)$[/tex] is equivalent to expression [tex]$\qquad$[/tex]
2. [tex]$\left(3x^2 - 4x - 4\right) + \left(-12x^2 + 2x + 11\right)$[/tex] is equivalent to expression [tex]$\qquad$[/tex]
3. [tex]$\left(4x^2 - 3x - 9\right) + \left(5x^2 + 5x + 2\right)$[/tex] is equivalent to expression [tex]$\qquad$[/tex]



Answer :

First, let's simplify each given expression step by step and match the results to the expressions A, B, and C.

### Expression 1: [tex]\( (7x^2 - 5x + 3) + (2x^2 + 3x - 1) \)[/tex]
1. Combine the like terms for [tex]\(x^2\)[/tex]:
[tex]\[ 7x^2 + 2x^2 = 9x^2 \][/tex]
2. Combine the like terms for [tex]\(x\)[/tex]:
[tex]\[ -5x + 3x = -2x \][/tex]
3. Combine the constant terms:
[tex]\[ 3 - 1 = 2 \][/tex]
So, the simplified expression is:
[tex]\[ 9x^2 - 2x + 2 \][/tex]

This matches with expression [tex]\(B\)[/tex].

### Expression 2: [tex]\( (3x^2 - 4x - 4) + (-12x^2 + 2x + 11) \)[/tex]
1. Combine the like terms for [tex]\(x^2\)[/tex]:
[tex]\[ 3x^2 - 12x^2 = -9x^2 \][/tex]
2. Combine the like terms for [tex]\(x\)[/tex]:
[tex]\[ -4x + 2x = -2x \][/tex]
3. Combine the constant terms:
[tex]\[ -4 + 11 = 7 \][/tex]
So, the simplified expression is:
[tex]\[ -9x^2 - 2x + 7 \][/tex]

This matches with expression [tex]\(A\)[/tex].

### Expression 3: [tex]\( (4x^2 - 3x - 9) + (5x^2 + 5x + 2) \)[/tex]
1. Combine the like terms for [tex]\(x^2\)[/tex]:
[tex]\[ 4x^2 + 5x^2 = 9x^2 \][/tex]
2. Combine the like terms for [tex]\(x\)[/tex]:
[tex]\[ -3x + 5x = 2x \][/tex]
3. Combine the constant terms:
[tex]\[ -9 + 2 = -7 \][/tex]
So, the simplified expression is:
[tex]\[ 9x^2 + 2x - 7 \][/tex]

This matches with expression [tex]\(C\)[/tex].

In summary:
- [tex]\( (7x^2 - 5x + 3) + (2x^2 + 3x - 1) \)[/tex] is equivalent to expression [tex]\( B \)[/tex].
- [tex]\( (3x^2 - 4x - 4) + (-12x^2 + 2x + 11) \)[/tex] is equivalent to expression [tex]\( A \)[/tex].
- [tex]\( (4x^2 - 3x - 9) + (5x^2 + 5x + 2) \)[/tex] is equivalent to expression [tex]\( C \)[/tex].

Thus, the completed statements are:
[tex]\[ \left(7 x^2-5 x+3\right)+\left(2 x^2+3 x-1\right) \text{ is equivalent to expression } \mathbf{B} \][/tex]
[tex]\[ \left(3 x^2-4 x-4\right)+\left(-12 x^2+2 x+11\right) \text{ is equivalent to expression } \mathbf{A} \][/tex]
[tex]\[ \left(4 x^2-3 x-9\right)+\left(5 x^2+5 x+2\right) \text{ is equivalent to expression } \mathbf{C} \][/tex]