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AP EAMCET · Maths · Differentiation

If y=1+1x1+2x1+3x1+nx and x0. When x=-1,dydx=

  1. A n !
  2. B (n-1) !
  3. C (-1)n(n-1)!
  4. D (-1)nn!
Verified Solution

Answer & Solution

Correct Answer

(C) (-1)n(n-1)!

Step-by-step Solution

Detailed explanation

Taking log on both sides we get logy=log1+1x+log1+2x.............log1+nx Differentiating, 1ydydx=11+1x-1x2+11+2x-2x2...........11+1n-nx2 dydx=-1+2x1+3x.....1+nx+21+1x1+2x....1+nxx2 Now put x=-1 dydx=-1(-1-2-3......1-n)1 dydx=-1n12.....n-1=-1nn-1!