Multiply :
`abx, -3a^(2)x` and `7b^(2)x^(3)`

Answer

To solve the problem of multiplying the expressions \( abx \), \( -3a^2x \), and \( 7b^2x^3 \), we will follow these steps:

### Step 1: Write down the expressions to be multiplied
We have:
\[ abx \times (-3a^2x) \times (7b^2x^3) \]

### Step 2: Multiply the first two expressions
First, we multiply \( abx \) and \( -3a^2x \):
\[ abx \times (-3a^2x) = a \times b \times (-3) \times a^2 \times x \times x \]
Now, we combine the like terms:
- The coefficients: \( 1 \times (-3) = -3 \)
- The \( a \) terms: \( a \times a^2 = a^{1+2} = a^3 \)
- The \( x \) terms: \( x \times x = x^{1+1} = x^2 \)

So, we have:
\[ -3a^3bx^2 \]

### Step 3: Multiply the result with the third expression
Now, we multiply \( -3a^3bx^2 \) with \( 7b^2x^3 \):
\[ (-3a^3bx^2) \times (7b^2x^3) = (-3) \times 7 \times a^3 \times b \times b^2 \times x^2 \times x^3 \]
Again, we combine the like terms:
- The coefficients: \( -3 \times 7 = -21 \)
- The \( a \) terms: \( a^3 \) (no other \( a \) terms to combine)
- The \( b \) terms: \( b \times b^2 = b^{1+2} = b^3 \)
- The \( x \) terms: \( x^2 \times x^3 = x^{2+3} = x^5 \)

So, we have:
\[ -21a^3b^3x^5 \]

### Final Result
The final result of multiplying \( abx \), \( -3a^2x \), and \( 7b^2x^3 \) is:
\[ \boxed{-21a^3b^3x^5} \]