Determine which polynomial is a perfect square trinomial.

A. [tex]25x^2 - 40x - 16[/tex]
B. [tex]9a^2 - 20a - 25[/tex]
C. [tex]25b^2 - 15b + 9[/tex]
D. [tex]16x^2 - 56x + 49[/tex]



Answer :

To determine which polynomial is a perfect square trinomial, we need to factor each polynomial and check if the factors can be expressed as the square of a binomial. Here are the polynomials given:

1. [tex]\(25x^2 - 40x - 16\)[/tex]
2. [tex]\(9a^2 - 20a - 25\)[/tex]
3. [tex]\(25b^2 - 15b + 9\)[/tex]
4. [tex]\(16x^2 - 56x + 49\)[/tex]

### 1. Polynomial [tex]\(25x^2 - 40x - 16\)[/tex]
First, let's attempt to factor [tex]\(25x^2 - 40x - 16\)[/tex]:
[tex]\[ 25x^2 - 40x - 16 \][/tex]
Checking the factorization, this polynomial does not simplify to the square of a binomial. Thus, it is not a perfect square trinomial.

### 2. Polynomial [tex]\(9a^2 - 20a - 25\)[/tex]
Next, we factor [tex]\(9a^2 - 20a - 25\)[/tex]:
[tex]\[ 9a^2 - 20a - 25 \][/tex]
Checking the factorization, this polynomial does not simplify to the square of a binomial. Thus, it is not a perfect square trinomial.

### 3. Polynomial [tex]\(25b^2 - 15b + 9\)[/tex]
For [tex]\(25b^2 - 15b + 9\)[/tex], let's try to factor it:
[tex]\[ 25b^2 - 15b + 9 \][/tex]
Checking the factorization, this polynomial does not simplify to the square of a binomial. Thus, it is not a perfect square trinomial.

### 4. Polynomial [tex]\(16x^2 - 56x + 49\)[/tex]
Lastly, we factor [tex]\(16x^2 - 56x + 49\)[/tex]:
[tex]\[ 16x^2 - 56x + 49 = (4x - 7)^2 \][/tex]
The factorization simplifies to [tex]\((4x - 7)^2\)[/tex], which is clearly the square of the binomial [tex]\(4x - 7\)[/tex].

Thus, the polynomial [tex]\(16x^2 - 56x + 49\)[/tex] is indeed a perfect square trinomial.

### Conclusion
The polynomial [tex]\(16x^2 - 56x + 49\)[/tex] is the perfect square trinomial. The other polynomials do not simplify to the squares of binomials and hence are not perfect square trinomials.