What value of n makes the equation true? open paren 2 x to the 9th power y to the n th power close paren times open paren 4 x squared y to the 10th power close paren is equal to 8 x to the 11th power y to the 20th power

Multiply the coefficients: 2 × 4 = 8. When multiplying powers with the same base, add their exponents, so the y exponent on the left is n + 10; matching it to the right side gives n + 10 = 20, hence n = 10. The correct choice is D, 10.

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