Posted by Yousef on Friday, October 21, 2011 at 5:42am.
1) Find d^2y / dx^2 given that y^3  x^2 = 4
2)If y = xª + ( 1 / xª ) , prove that
x^2 . y'' + xy' – a^2 . y = 0
3) Find dy/dx for the following function.
cos ( x  y ) = ( y ) ( 2x + 1 ) ^3
4)Find the values of A and B that make f(x) differentiable at
x = 0
f(x) = A + 2x + 3, if x > 0
AND
f(x) = 5 + B (sin²x / x) , if x < 0

Maths Derivatives & Calulus  Steve, Friday, October 21, 2011 at 12:41pm
y^3  x^2 = 4
3y^2 y'  2x = 0
y' = 2x/3y^2
6y y'^2 + 3y^2 y''  2 = 0
y'' = (2  6yy'^2)/3
= (2  6y(2x/3y^2)^2)/3
_______________
y = x^a + 1/x^a
y' = ax^(a1)  a/x^(a+1)
y'' = a(a1)x^(a2) + a(a+1)/x^(a+2)
x^2 y'' = a(a1)x^a + a(a+1)/x^a
xy' = ax^a  a/x^a
a^2 y = a^2 x^a  a^2/x^a
Add 'em up: 0
_______________
cos(xy) = y(2x+1)^3
sin(xy)(1y') = y'(2x+1)^3 + 6y(2x+1)^2
y'(sin(xy)  y'(2x+1)^3 = xsin(xy) + 6y(2x+1)^2
carry on
__________________
lim sin^2 x/x = 2sincos/1 = 0
f(0) = A + 3
f(0) = 5 + 0B = 5
So, if A=2, then the limit exists from both sides

Maths Derivatives & Calulus  Yousef, Saturday, October 22, 2011 at 8:53am
thank u so much for ur effort and time
helped me alot!!!!!
Answer This Question
Related Questions
 Maths Derivatives  If y = x ^ n + ( 1 / x ^ n ) prove that ( x^2y'' ) + ( xy...
 convert derivatives of x,y,z, to r, Ɵ,z  convert derivatives of x,y,z, to ...
 Calculus  show that the curves r=asin(è) and r=acos(è) intersect at right ...
 math  I studied derivatives before, but kind of forgot them all, is there a ...
 Geometry  Can you just help me with this thanks Directions: Tell which property...
 Maths  Find the derivatives of these: f(x)=√
 maths  Given that a,b,c >0 Prove : (a/b + b/c +c/a)(b/a +c/b +a/c)>0
 maths  find the maximum valu of any of the function without using derivatives ...
 Maths  Is given a function: f(x)=x2 + px + q Prove that: f(x+1) + f(x1)= 2+2 f...
 Derivatives  Find the derivatives of: 1. H(x)= sin2xcos2x The answer given is ...
More Related Questions