Combinations

From how many elements we can create 990 combinations 2nd class without repeating?

Correct answer:

n =  45

Step-by-step explanation:

(n2)=n(n1)2=990;n>0 n2n1980=0  a=1;b=1;c=1980 D=b24ac=1241(1980)=7921 D>0  n1,2=b±D2a=1±79212 n1,2=1±892 n1,2=0.5±44.5 n1=45 n2=44   Factored form of the equation:  (n45)(n+44)=0   n>0n=45



Did you find an error or inaccuracy? Feel free to write us. Thank you!



avatar







Tips to related online calculators
Looking for help with calculating roots of a quadratic equation?
Would you like to compute count of combinations?

You need to know the following knowledge to solve this word math problem:

Related math problems and questions:

  • 2nd class combinations
    color_circle From how many elements you can create 4560 combinations of the second class?
  • Combinations
    kvadrat If the number of elements increase by 3, it increases the number of combinations of the second class of these elements 5 times. How many are the elements?
  • Combinations
    trezor How many elements can form six times more combinations fourth class than combination of the second class?
  • Variations 3rd class
    cubic From how many elements we can create 13,800 variations 3rd class without repeating?
  • 2nd class variations
    cards From how many elements you can create 2450 variations of the second class?
  • Variations 4/2
    pantagram Determine the number of items when the count of variations of fourth class without repeating is 600 times larger than the count of variations of second class without repetition.
  • Combinations 6
    dices2 6 purses 9 flaps 12 straps Every combination must include 1 purse, 1 flap, and 1 strap. How many are possible combinations?
  • Elements
    fact If the number of elements is decreased by two the number of permutations is decreased 30 times. How many elements are?
  • Two-element combinations
    combinatorics Write all two-element combinations from elements a, b, c, d.
  • VCP equation
    combinatorics3 Solve the following equation with variations, combinations and permutations: 4 V(2,x)-3 C(2,x+ 1) - x P(2) = 0
  • Class pairs
    pair In a class of 34 students, including 14 boys and 20 girls. How many couples (heterosexual, boy-girl) we can create? By what formula?
  • Martina
    eq1 Martina is solving the equation 4x - 11 = 2x + 391. Here are the first steps of her solution. 4x - 11 = 2x + 391 2x - 11 = 391 2x = 402 What did Martina do to get 2x - 11 = 391?
  • Statistics
    lines_globe The sum of all deviations from the arithmetic mean of the numerical sequence 4, 6, 51, 77, 90, 93, 95, 109, 113, 117 is:
  • Family
    family 94 boys are born per 100 girls. Determine the probability that there are two boys in a randomly selected family with three children.
  • I think number
    hats I think number.When I add 841 to it and subtract 157, I get a number that is 22 greater than 996. What number I thinking?
  • A photograph
    photo A photograph will stick to a white square letter with a x cm length. The photo is 3/4 x cm long and 20 cm wide than the width of the paper. The surface of the remaining paper surrounding the photograph is 990 cm2. Find the size of paper and photo.
  • Party
    party-informatikov At the party everyone clink with everyone. Together, they clink 406 times. How many people were at the party?