# Derivatives question

• May 9th 2008, 03:55 AM
Derivatives question
Kindly help me with this questions.

Obtain the derivatives for the following funtions using the delta method
1.y=3/4
2.y=20x^3-12x^2+4x-7/18

Obtain the derivatives below using rules of differentiation

1.55x^15-11e^x2+8lnx^4+8x^-15-3/4x^5/7

2.y=(2x^3-4x^2)ln(x^4-7x^2)

3.y=(6.8ex^3+4x^2)/(9ln(x^2-7x))

4.y=(3e^(4x-10)4(lnx^3-2x)^7
• May 9th 2008, 04:10 AM
flyingsquirrel
Hi
Quote:

Obtain the derivatives for the following funtions using the delta method
1.y=3/4
2.y=20x^3-12x^2+4x-7/18

In both cases, your expected to use the definition of the derivative : $f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}$. The first derivative should be quite easy to find and for the second one you'll need $(x+h)^3=x^3+3x^2h+3xh^2+h^3$ and $(x+h)^2=x^2+2xh+h^2$
Quote:

Obtain the derivatives below using rules of differentiation

1.55x^15-11e^x2+8lnx^4+8x^-15-3/4x^5/7

2.y=(2x^3-4x^2)ln(x^4-7x^2)

3.y=(6.8ex^3+4x^2)/(9ln(x^2-7x))

4.y=(3e^(4x-10)4(lnx^3-2x)^7
What's the problem with these ones ?
• May 9th 2008, 05:49 AM
Quote:

Originally Posted by flyingsquirrel
Hi

In both cases, your expected to use the definition of the derivative : $f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}$. The first derivative should be quite easy to find and for the second one you'll need $(x+h)^3=x^3+3x^2h+3xh^2+h^3$ and $(x+h)^2=x^2+2xh+h^2$
What's the problem with these ones ?

Thanks for your help.i am so new to this kind of mathematics.with the second ones we need to use some rules which i dont know
• May 9th 2008, 06:21 AM
flyingsquirrel
Quote:

• product rule : $\left(u(x)\cdot v(x)\right)'=u'(x)\cdot v(x)+v'(x)\cdot u(x)$
• quotient rule : $\left(\frac{u(x)}{v(x)}\right)'=\frac{u'(x)\cdot v(x)-v'(x)\cdot u(x)}{v^2(x)}$
• chain rule : $\left(u\circ v(x)\right)'=v'(x)\cdot u'\circ v(x)$
• $(x^n)'=n\cdot x^{n-1}$
• $(\ln x)'=\frac{1}{x}$
• $(\exp x)'=\exp x$