Math Problem Statement

given (a,b,c,d,e) are all integers and all of them are greater than 10, find the number of solution sets of (a+b+c+d+e)=83

Solution

To solve the equation a+b+c+d+e=83a + b + c + d + e = 83, where aa, bb, cc, dd, and ee are integers greater than 10, we need to transform the equation into a simpler form.

Step 1: Change of Variables

Let: a=a11,b=b11,c=c11,d=d11,e=e11a' = a - 11, \quad b' = b - 11, \quad c' = c - 11, \quad d' = d - 11, \quad e' = e - 11 where a,b,c,d,e0a', b', c', d', e' \geq 0. This transformation shifts the variables so that they are non-negative integers.

Thus, the original equation becomes: (a+11)+(b+11)+(c+11)+(d+11)+(e+11)=83(a' + 11) + (b' + 11) + (c' + 11) + (d' + 11) + (e' + 11) = 83 Simplifying: a+b+c+d+e=28a' + b' + c' + d' + e' = 28 Now, we need to count the number of non-negative integer solutions to the equation a+b+c+d+e=28a' + b' + c' + d' + e' = 28.

Step 2: Stars and Bars

The number of non-negative integer solutions to an equation of the form x1+x2++xk=nx_1 + x_2 + \dots + x_k = n is given by the stars and bars formula: Number of solutions=(n+k1k1)\text{Number of solutions} = \binom{n + k - 1}{k - 1} In this case, n=28n = 28 and k=5k = 5 (since there are 5 variables a,b,c,d,ea', b', c', d', e'). Thus, the number of solutions is: (28+5151)=(324)\binom{28 + 5 - 1}{5 - 1} = \binom{32}{4}

Step 3: Calculate (324)\binom{32}{4}

(324)=32×31×30×294×3×2×1=32×31×30×2924\binom{32}{4} = \frac{32 \times 31 \times 30 \times 29}{4 \times 3 \times 2 \times 1} = \frac{32 \times 31 \times 30 \times 29}{24} (324)=86304024=35960\binom{32}{4} = \frac{863040}{24} = 35960

Final Answer

Thus, the number of solution sets for the equation a+b+c+d+e=83a + b + c + d + e = 83 is 35,960.


Would you like more details on any of the steps or calculations?

Here are some related questions:

  1. How does the stars and bars method work in combinatorics?
  2. What is the general formula for counting non-negative integer solutions in an equation?
  3. Can we apply this method to equations with different variable restrictions?
  4. What if one of the variables had to be at least 20 instead of 10?
  5. How does this method apply if we are working with modular arithmetic?

Tip: When solving integer equations with constraints like xikx_i \geq k, a variable shift can simplify the problem into one with non-negative integers.

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Math Problem Analysis

Mathematical Concepts

Combinatorics
Integer Solutions
Non-negative Integer Equations

Formulas

Stars and Bars Formula: C(n + k - 1, k - 1)
Binomial Coefficient Formula: C(n, r) = n! / (r! * (n - r)!)

Theorems

Stars and Bars Theorem

Suitable Grade Level

Grades 11-12