CBSE 11TH MATHEMATICS - Online Test

Total ways of getting 6 heads out of 8 toss of coins is 28.

Total number of outcome is 28 = 256

Therefore probability is  28256=764

Number of ways of forming 5 digit numbers= 5×4×3×2×1=120

 Number of ways of forming 4 digit numbers= 5×4×3×2=120

Number of ways of forming 3 digit numbers= 5×4×3=60

Number of ways of forming 2 digit numbers=5×4=20

Number of ways of forming 1 digit numbers= 5

Hence the total number of ways = 120+ 120 + 60+ 20+ 5 = 325

Given x ∈$\in$ R and x <$<$ 0, therefore  the number is −x+0i and this will be a point inthe second quadrant as x is negative 

We have arg(−x+0i=θ=  tan−1∣∣yx∣∣=tan−1∣∣0−1∣∣=tan−10=0

We have in the second quadrant the principal value of argument=  Π−θ=​​​​​​Π−0=Π

Hence Arg. ( x ) , x ∈ R and x < 0 is π

here,

an=2n(2n+2)a20=2(20)(2.20+2)=40(42)=1680