If x - 1/x = 1 then what is the value of 1x1x-1-1x+1+1x2+1-1x2-1?

Correct Answer: y

Correct Answer: 5?3

Correct Answer: 1

Correct Answer: 2m ?m^2/n

Explanation:

Mean of m observations is n

Mean of n-m observations is m

So total = nm+ (n-m)m

Total observations = n

Mean = Total / Total observations = (2mn-m^2)/n = 2m ?m^2/n

 

Correct Answer: 20 cm

Explanation:

Let there be 2 circles with centre O1 and OAB is the common chord

Since both passes through the center of each other as shown in figure

So O1O is the radius of both

Let O1O = r = AO1= AO

AX = AB / 2 = 5?3 cm (since OX perpendicular to chord bisects it)

AOO1 forms an equilateral triangle with on side = radius = r

Sin 60 = ?3/2 = AX / AO = 5?3/r

So r = 10 cm

So diameter = 20 cm

 

Correct Answer: 17/31

Correct Answer: Both 1/2 and 5/2

Correct Answer: 1

Correct Answer: 2/y

Correct Answer: 56

Explanation:

In the below equation,

x2?15x + r = 0

sum of roots = p + q = -(-15)/1 = 15 (sum of roots for equation ax2+ bx + c is -b/a)

product of roots = pq = r/1 = r     (product of roots for equation ax2+ bx + c is c/a)

given p ?q = 1

also we know that p+q = 15

subtracting the squares of both

(p+q)2 + (p-q)2 = 15^2?1

p2 + q2 + 2pq ?p2 ?q2 +2pq = 225 -1

4pq = 224

4r = 224

r = 56