" 3.Prove that "(1)/(10!)+(1)/(11!)+(1)/(12!)=(145)/(12!)

Prove that: (1)/(9!)+(1)/(10!)+(1)/(11!)=(122)/(11!)

Prove that: 1/(9!)+1/(10 !)+1/(11 !)=(122)/(11 !)

If A= |(3,2,-1),(1,0,2),(-2,1,2)| Prove that (i) a_(11)A_(11)+a_(12)A_(12)+a_(13)A_(13)=det(A) (ii) a_(21)A_(11)+a_(22)A_(12)+a_(23)A_(13)=0

tan ^(-1) (1/11)+tan ^(-1)(2/12)=

2(1)/(4)+1(1)/(3)-4(1)/(2)=?-1(1)/(12) (b) (11)/(12) (c) -(11)/(12)(d)1(1)/(12) (e) None of these

If (1)/(1(1)/(4)) + ( 1)/( 6(2)/(3)) - ( 1)/( x) + ( 1)/( 10) = (11)/( 12) , then find the value of x

Prove that : cos^(-1).(3)/(5)+ cos^(-1).(12)/(13) = sin^(-1)((12)/(5))

(5 1/4-3 1/3)= (12)/(23) (b) 2 1(11)/(12) (d) (11)/(12)

Prove that tan (pi/12)tan((5pi)/12)tan ((7pi)/12)tan((11pi)/12)=1