IIT JEE , AIEEE Forum - Mathematics , Differential Calculus - AWESOME QNS. IN DIFFERENTIAL...........................

shubham_sachdeva

2. if y = cos ax , show that | y y1 y2 |

|y3 y4 y5 | = 0 (| | means determinant)

|y6 y7 y8 |

where yr(e.g y1,y2,y2...y8) yr = d^r(cos ax)

dx^r

3. find the sum

_{[ n = 1]}^{[infinity ]} (n^2 . x^n-1 , | x | < 1 , using calculas..

4. let y = f(x) . g(x) and z = f ' (x) . g ' (x)

the prove that

1 . d^2y = 1 . d^2f + 1 . d^2g + 2z

y dx^2 f dx^2 g dx^2 f.g

hope u will enjoy these qns.

shubham_sachdeva

guyzzzzzzzzz & galzzzzzzzzz

(experts too)
plzzzzzzzzzz answer ..........................................

shubham_sachdeva

cmmon plzzzzzzzz help.....is dere noone here who hav guts to solve dis.....

plzzzzzzzzzzzzzzzzzzzzzzzz solve..

vinu

Hi shubhu,

4)its very easy....

jus differentiate 'y' two times and divide both sides by 'y'...u get the result...

2)this one too...yr = a^r * cos[ax+(rpi/2)] ;

u'll observe tht all the rows in the det r same takin a³,a⁶ common frm 2nd,3rd rows resp.....

hence,det = 0 .