Math Problem Statement

a+b+c - 6 , ab + bc+ ca - 11 Find the value of a3+b3 + c3

Solution

You have two given equations involving aa, bb, and cc:

  1. a+b+c=6a + b + c = 6
  2. ab+bc+ca=11ab + bc + ca = 11

We need to find the value of a3+b3+c3a^3 + b^3 + c^3.

To proceed, we can use the identity for the sum of cubes of three variables:

a3+b3+c33abc=(a+b+c)((a+b+c)23(ab+bc+ca))a^3 + b^3 + c^3 - 3abc = (a + b + c)((a + b + c)^2 - 3(ab + bc + ca))

Let's break it down step by step:

Step 1: Calculate (a+b+c)2(a + b + c)^2

(a+b+c)2=62=36(a + b + c)^2 = 6^2 = 36

Step 2: Compute (a+b+c)23(ab+bc+ca)(a + b + c)^2 - 3(ab + bc + ca)

363×11=3633=336 - 3 \times 11 = 36 - 33 = 3

Step 3: Use the identity for a3+b3+c3a^3 + b^3 + c^3

a3+b3+c33abc=(a+b+c)×3=6×3=18a^3 + b^3 + c^3 - 3abc = (a + b + c) \times 3 = 6 \times 3 = 18 Thus, a3+b3+c3=18+3abca^3 + b^3 + c^3 = 18 + 3abc

To find the exact value of a3+b3+c3a^3 + b^3 + c^3, we need to know the value of abcabc. Without this, we can only express the result in terms of abcabc.

So the final expression is: a3+b3+c3=18+3abca^3 + b^3 + c^3 = 18 + 3abc

Would you like help finding abcabc or any other detail?

Related questions:

  1. How do we calculate abcabc from these equations?
  2. Can you derive the identity for a3+b3+c3a^3 + b^3 + c^3?
  3. What happens if a=b=ca = b = c?
  4. How would the result change if the constants in the original equation were different?
  5. Can this method be applied to find higher powers of a+b+ca + b + c?

Tip: Memorize the identity for the sum of cubes when dealing with symmetric expressions—it saves a lot of time!

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Math Problem Analysis

Mathematical Concepts

Algebra
Sum of Cubes Identity
Symmetric Equations

Formulas

(a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca)
a^3 + b^3 + c^3 - 3abc = (a + b + c)((a + b + c)^2 - 3(ab + bc + ca))

Theorems

Sum of Cubes Theorem

Suitable Grade Level

Grades 10-12