Question 1: f(x)=8/x at x=-1 Answer A: f\'(x)=8/x^2; f\'(-1)=8 B: f\'(x)=-8x^2;

Question

Question 1: f(x)=8/x at x=-1

Answer A: f'(x)=8/x^2; f'(-1)=8

B: f'(x)=-8x^2; f'(-1)=-8

C: f'(x)=-8/x^2; f'(-1)=-8

D: f'(x)=8; f'(-1)=8

Question 2: f(x)=5x^2+x at x=-4

Answer A: f'(x)=x-10; f'(-4)=-14

B: f'(x)=x+10; f'(-4)=6

C: f'(x)=10x+1; f'(-4)=-39

D: f'(x)=10x-1; f'(-4)=-41

Question 3: f(x)=x^2+5x at x=4

Answer A: f'(x)=2x+5; f'(4)=13

B: f'(x)=x+5; f'(4)=9

C: f'(x)=4x+5; f'(4)=21

D: f'(x)=2x-5; f'(4)=3

Question 4: f(x)=x^2+11x-15 at x=1

Answer A: f'(x)=11x;f'(1)=11

B: f'(x)=11x+15;f'(1)=26

C: f'(x)=2x-11;f'(1)=-9

D: f'(x)=2x+11x;f'(1)=13

Question 5: f(x)=3x^2+5x-7 at x=-2

Answer A: f'(x)=2x+5;f'(-2)=1

B: f'(x)=6x+5;f'(-2)=-7

C: f'(x)=3x+5;f'(-2)=-1

D: f'(x)=6x-5;f'(-2)=-17

Explanation / Answer

For f(x)=x^n (n belongs to R) ,,  f'(x)=n*x^(n-1)

Question 1: f(x)=8/x at x=-1

Answer : C: f'(x)=-8/x^2; f'(-1)=-8/(-1)^2 = -8

Question 2: f(x)=5x^2+x at x=-4

Answer : C: f'(x)=10x+1; f'(-4) = 10*(-4)+1 = -39

Question 3: f(x)=x^2+5x at x=4

Answer :  A: f'(x)=2x+5; f'(4) = 2*4+5 = 13

Question 4: f(x)=x^2+11x-15 at x=1

Answer : f'(x)=2x+11;f'(1) = 2*1+11 = 13

Question 5: f(x)=3x^2+5x-7 at x=-2

Answer : B: f'(x)=6x+5;f'(-2) = 6*(-2)+5 = -7

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