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IfF(x) = f(xf(xf(x))),wheref(1) = 5, f(5) = 6, f '(1) = 2, f '(5) = 3,andf '(6) = 4,findF '(1).

1 Answer

4 votes

Answer:

F'(1)=108

Explanation:

F(x) = f(xf(xf(x)))

Lets take

g(x)= x f(x)

F(x) = f(xf(g(x)))

h(x)=f(g(x))

F(x) = f(xh(x))

m(x)= xh(x)

F(x) = f(xh(x)) = f(m(x))

F'(x)= f'(m(x)) m'(x)

F'(1)= f'(m(1)) m'(1)

m(x)= x h(x)

m'(x)= h(x)+x h'(x)

h(x)=f(g(x))

h'(x)=f'(g(x)) g'(x)

g(x)= x f(x)

g'(x)= f(x)+x f'(x)

F'(1)= f'(m(1)) m'(1)

m'(1)= h(1)+1 h'(1)

h'(1)=f'(g(1)) g'(1)

g'(1)= f(1)+1 f'(1)

Now by putting the values

g'(1)= f(1)+1 f'(1) = 5 + 1 x 2 = 7

h'(1)=f'(g(1)) g'(1)

g(x)= x f(x) , g(1)= 1 f(1) = 5

h'(1)=f'(5) g'(1) = 3 x 7 =21

m'(1)= h(1)+1 h'(1)

h(x)=f(g(x)) , h(1) = f(g(1)) = f(5) = 6

m'(1)= h(1)+1 h'(1)

m'(1)=6+1 x 21

m'(1)=27

F'(1)= f'(m(1)) m'(1)

m(x)= x h(x) ,m(1)= 1 h(1) = 6

F'(1)= f'(6) m'(1)

F'(1)= f'(6) m'(1) = 4 x 27 =108

F'(1)=108

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