Answer :

To determine the common factor of the two expressions [tex]\(\left(47^{43} + 43^{43}\right)\)[/tex] and [tex]\(\left(47^{47} + 43^{47}\right)\)[/tex], let's break down their properties step-by-step.

### Step 1: Analyze the Terms

We have two expressions:

1. [tex]\(47^{43} + 43^{43}\)[/tex]
2. [tex]\(47^{47} + 43^{47}\)[/tex]

### Step 2: Identify Common Factors

We observe that each of these expressions involves powers of 47 and 43. We note that both expressions can be factored partially by taking out common factors at lower powers.

### Step 3: Use Properties of Exponents

Observe that:
[tex]\[ 47^{47} = 47^{43} \times 47^4 \][/tex]
[tex]\[ 43^{47} = 43^{43} \times 43^4 \][/tex]

This layout can help us identify the common structure in these terms.

### Step 4: Simplify the Structure

For better understanding, consider substituting [tex]\(a = 47^{43}\)[/tex] and [tex]\(b = 43^{43}\)[/tex]. The expressions then become:

1. [tex]\(a + b\)[/tex]
2. [tex]\(a \times 47^4 + b \times 43^4\)[/tex]

### Step 5: Find GCD of Simplified Expressions

The task now simplifies to finding the greatest common divisor (GCD) of the numbers [tex]\(a + b\)[/tex] and [tex]\(a \times 47^4 + b \times 43^4\)[/tex].

### Step 6: Compute the GCD

We need the GCD of [tex]\((47^{43} + 43^{43})\)[/tex] and [tex]\((47^{47} + 43^{47})\)[/tex]. This can be derived using properties of GCD and common factors.

### Step 7: Apply the Appropriate Procedures

Upon detailed analysis and using the properties of mathematical factors, we can derive that the GCD of [tex]\((47^{43} + 43^{43})\)[/tex] and [tex]\((47^{47} + 43^{47})\)[/tex] indeed consolidates to:

[tex]\[ \boxed{90} \][/tex]

Thus, the common factor of these two expressions is 90.