Answer :

Let's break down the multiplication of the two expressions step-by-step:

We need to find the product of \((9t - 4)\) and \((-9t - 4)\).

Step 1: Use the distributive property \(a(b + c) = ab + ac\) to multiply each term in the first polynomial by each term in the second polynomial.

[tex]\[ (9t - 4)(-9t - 4) = 9t \cdot (-9t) + 9t \cdot (-4) + (-4) \cdot (-9t) + (-4) \cdot (-4) \][/tex]

Step 2: Perform the multiplications:

[tex]\[ 9t \cdot (-9t) = -81t^2 \][/tex]
[tex]\[ 9t \cdot (-4) = -36t \][/tex]
[tex]\[ (-4) \cdot (-9t) = 36t \][/tex]
[tex]\[ (-4) \cdot (-4) = 16 \][/tex]

Step 3: Combine all the terms:

[tex]\[ -81t^2 + (-36t) + 36t + 16 \][/tex]

Step 4: Simplify by combining like terms, namely the \(-36t\) and \(+36t\) terms:

[tex]\[ -81t^2 - 36t + 36t + 16 \][/tex]

Since \(-36t + 36t = 0\), they cancel out, leaving us with:

[tex]\[ -81t^2 + 16 \][/tex]

Thus, the product of \((9t - 4)\) and \((-9t - 4)\) is:

[tex]\[ \boxed{-81t^2 + 16} \][/tex]