Posted by **Roy** on Tuesday, September 17, 2013 at 6:15am.

Find dy/dx, if y= 5e^x/cosx

- calculus -
**Jai**, Tuesday, September 17, 2013 at 6:53am
y = (5e^x)/(cos x)

Since 1/cos(x) = sec(x), we can also rewrite this as

(5e^x)(sec(x))

Since two terms which are both functions of x are multiplied, we use the chain rule. Thus it becomes:

(5e^x)(sec(x)) + (5e^x)(tan(x) * sec(x))

Simplifying,

dy/dx = (5e^x)(sec(x))(1 + tan(x))

Hope this helps~ :3

- calculus -
**Graham**, Tuesday, September 17, 2013 at 7:04am
Let f(x) = e^x

So f'(x) = e^x

Let g(x) = cos(x)

So g'(x) = -sin(x)

Use:

(f/g)' = ((f'×g)-(f×g'))/g^2

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