Mathematics OpenStudy (anonymous):

find the derivative of f(x) = 7x^3. I think the answer should be 21x^2 but I'm getting 7x^2. I will put my workings underneath. myininaya (myininaya):

(cf)'=cf' you know this rule? f'(x)=7(x^3)'=7*3x^2=21x^2 OpenStudy (anonymous):

7x^3 - 7(x + h)^3/h - this may be the problem 7x^3 - 7x^3 + 7x^2h + 7xh^2 + 7h^3/h - or this 7x^2 + 7xh + 7h^2 make h 0 7x^2 myininaya (myininaya):

also do you know (x^n)'=nx^(n-1) power rule OpenStudy (anonymous):

Yeah I am thinking that I am wrong because when I apply the shortcut version it is wrong. But I want to understand how to do it in the long sense so I can do hard ones later.. OpenStudy (anonymous):

Oh I only know your second rule, not the first one myininaya (myininaya):

k f(x)=7x^3 f(x+h)=7(x+h)^3=7(x^3+3x^2h+3xh^2+h^3)=7x^3+21x^2h+21xh^2+7h^3 myininaya (myininaya):

$\frac{(7x^3+21x^2h+21xh^2+7h^3)-(7x^3)}{h}$ myininaya (myininaya):

$\frac{21x^2h+21xh^2+7h^2}{h}$ OpenStudy (anonymous):

Ahhh... again the binomial theory defeats me! I didn't put the 3's when I expanded it... Thankyou! myininaya (myininaya):

$\frac{h(21x^2+21xh+7h)}{h}$ myininaya (myininaya):

k so you got the rest? OpenStudy (anonymous):

I think I'm good, I see where I went wrong now :) Thanks :) myininaya (myininaya):

:)

Latest Questions hannahj: Which of the following is the complete list of roots for the polynomial function f (x) = (x squared + 6 x + 8) (x squared + 6 x + 13)? 1.
27 minutes ago 1 Reply 0 Medals montes67: I need a scenario where all of Earth's spheres (bio, geo, atmos, hydro, magneto) interact with one another.
4 minutes ago 2 Replies 0 Medals Mochi: How can including community service into college course curriculum change the way students learn? Answer in a one sentence thesis statement.
35 seconds ago 6 Replies 1 Medal antman1: Utilize any or all of the 3 modes of persuasion in your campaign: ethos, pathos, logos Ethos - credentials, speaker (or company) established as a credible s
24 minutes ago 3 Replies 0 Medals aw3someness37: Please help! I am timed. Which of the following is the complete list of roots for the polynomial function f (x) = (x squared + 6 x + 8) (x squared + 6 x + 1
27 minutes ago 3 Replies 1 Medal Mochi: How has computer technology changed the way people communicate with one another? Answer in a one sentence thesis statement.
43 minutes ago 3 Replies 1 Medal LaylaSanaii: Point A is located at negative 6 over 8 and point B is located at negative 1 over 8.
1 hour ago 5 Replies 1 Medal Tinygirljaleax1: how to work out 9u00f71.034
1 hour ago 0 Replies 0 Medals DiabolikLover: Can someone check my work and make sure it reads ok? In my research, I have found 3 questions that would prove to be the most important to answer before sta
1 hour ago 2 Replies 1 Medal MarkSucks: Help pls :0 A jet made a trip to Jakarta and back. The trip there took 11 hours and the trip back took nine hours.
1 hour ago 1 Reply 0 Medals