B is true
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F(x) = cos x
f'(x) = -sin x
f''(x) = -cos x
f'''(x) = sin x
f''''(x) = cos x
90/4 = 22 Remainder 2
Therefore, 90th derivative of f(x) = cos x is -cos x.
So you have 5.36
that is 5 wholes and 0.36
0.36 can be written on a fraction of 36/100
simplify it to 9/25
Now you have the mixed number
5 9/25 or to write it into an improper fraction... multiply 25 * 5 then add 9, that is 134/25.
Hope this helps
