Advertisements
Advertisements
प्रश्न
At an annual function of a school, each student gives the gift to every other student. If the number of gifts is 1980, find the number of students.
Advertisements
उत्तर
Let the number of students = x
then the number of gifts given = x – 1
Total number of gifts = x (x – 1)
According to the condition,
x (x – 1) = 1980
⇒ x2 - x - 1980 = 0
⇒ x2 - 45x + 44x - 1980 = 0
⇒ x(x - 45) + 44(x - 45) = 0
⇒ (x - 45)(x + 44) = 0
Either x - 45 = 0,
then x = 45
or
x + 44 = 0,
then x = -44,
but it is not possible as it is negative.
Hence number of students = 45.
APPEARS IN
संबंधित प्रश्न
Find the roots of the following quadratic equation by factorisation:
x2 – 3x – 10 = 0
Two numbers differ by 3 and their product is 504. Find the number
A train covers a distance of 90 km at a uniform speed. Had the speed been 15 km/hour more, it would have taken 30 minutes less for a journey. Find the original speed of the train.
Some students planned a picnic. The budget for food was Rs. 500. But, 5 of them failed to go and thus the cost of food for each member increased by Rs. 5. How many students attended the picnic?
The sum of the squares to two consecutive positive odd numbers is 514. Find the numbers.
If x = 1 is a common root of ax2 + ax + 2 = 0 and x2 + x + b = 0, then, ab =
If one root the equation 2x2 + kx + 4 = 0 is 2, then the other root is
Solve the following equation:
`(x - 1)/(2x + 1) + (2x + 1)/(x - 1) = 5/2 , x ≠-1/2`
Solve equation using factorisation method:
`x + 1/x = 2.5`
If the perimeter of a rectangular plot is 68 m and the length of its diagonal is 26 m, find its area.
