Simplify the Expression: (5^7 × 4^7) ÷ 19^7

To solve this problem, we need to simplify the expression $\frac{5^7 \times 4^7}{19^7}$.

We start by applying the property of exponents which states that for any numbers $a$, $b$, and $c$, $a^c \times b^c = (a \times b)^c$. In this case, we have:

$5^7 \times 4^7 = (5 \times 4)^7$

Thus, the original expression becomes:

$\frac{(5 \times 4)^7}{19^7}$

Now, using the exponent rule for powers of a fraction, $\left(\frac{a}{b}\right)^c = \frac{a^c}{b^c}$, this further simplifies as:

$\left(\frac{5 \times 4}{19}\right)^7$

Therefore, when we look at the answer choices, both options:

• $\frac{(5 \times 4)^7}{19^7}$
• $\left(\frac{5 \times 4}{19}\right)^7$

are equivalent to our simplified expression. This corresponds to choice B and choice C in the given question. Therefore, both B and C are correct.

To conclude, the correct answer is $\text{B+C are correct}$.