(7а4b)2 =

To simplify \((7a^4b)^2\):

1. Apply the exponent to each part inside the parentheses: \[ (7a^4b)^2 = 7^2 \cdot (a^4)^2 \cdot b^2 \]

2. Now calculate each part:

   • \(7^2 = 49\)
   • \((a^4)^2 = a^{4 \cdot 2} = a^8\)
   • \(b^2 = b^2\)

3. Combine the results: \[ 49a^8b^2 \]

Thus, \((7a^4b)^2 = 49a^8b^2\).