Find the square of:
`3a-4b`

Answer

To find the square of \( 3a - 4b \), we will use the formula for the square of a binomial, which states:

\[ (x - y)^2 = x^2 - 2xy + y^2 \]

Here, we can identify \( x = 3a \) and \( y = 4b \). Now, let's apply the formula step by step.

### Step 1: Identify \( x \) and \( y \)
Let:
- \( x = 3a \)
- \( y = 4b \)

### Step 2: Apply the formula
Using the formula \( (x - y)^2 = x^2 - 2xy + y^2 \):

\[ (3a - 4b)^2 = (3a)^2 - 2(3a)(4b) + (4b)^2 \]

### Step 3: Calculate \( (3a)^2 \)
\[ (3a)^2 = 9a^2 \]

### Step 4: Calculate \( (4b)^2 \)
\[ (4b)^2 = 16b^2 \]

### Step 5: Calculate \( -2(3a)(4b) \)
\[ -2(3a)(4b) = -24ab \]

### Step 6: Combine all the terms
Now, substituting back into the equation:

\[ (3a - 4b)^2 = 9a^2 - 24ab + 16b^2 \]

### Final Answer
Thus, the square of \( 3a - 4b \) is:

\[ 9a^2 - 24ab + 16b^2 \]

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