If `a=-9, d= -7`, then `t_(19)` =

A d d7/9a n d(-12)/9

A d d7/9a n d(-12)/9

If in G.P ., t_5:t_3=7:9 then t_9:t_5 is

If the mean of and 7 is 7, then 6 (b) 7 8 (d) 9

Find d for an A.P. if (i) t_(10) =20, t_(9) = 18 (ii) t_(n) = 7, t_(n-1) = 10

In Figure, Q R is a common tangent to the given circles touching externally at the point T . The tangent at T meets Q R at P . If P T=3. 8 c m , then the length of Q R (in cm) is (a) 3.8 (b) 7.6 (c) 5.7 (d) 1.9

If the mean of 6,\ 7,\ x ,\ 8,\ y ,\ 14 is 9, then (a) x+y=21 (b) x+y=19 (c) x-y=19 (d) x-y=21

If the mean of 6,\ 7,\ x ,\ 8,\ y ,\ 14 is 9, then (a) x+y=21 (b) x+y=19 (c) x-y=19 (d) x-y=21

Let y=x^(3)-8x+7 and x=f(t). If (dy)/(dt)=2 and x=3 at t=0, then (dx)/(dt) at t=0 is given by 1 (b) (19)/(2)(c)(2)/(19) (d) none of these