All Exams Test series for 1 year @ ₹349 only
Question

\(\frac{885\times885\times885+115\times115\times115}{885\times885+115\times115-885\times115}=\)

This question was previously asked in
UPSSSC PET 2021 Question Paper (24-Aug-2021) (Shift 2)
The correct answer is
1000

Solving Algebraic Simplification: The Sum of Cubes

This problem involves simplifying a complex-looking mathematical expression using a fundamental algebraic identity. We need to evaluate the expression:

$$ \frac{885 \times 885 \times 885 + 115 \times 115 \times 115}{885 \times 885 + 115 \times 115 - 885 \times 115} $$

Directly calculating the cubes and products would be very time-consuming. Instead, we can recognize that this expression fits a known algebraic pattern.

Leveraging the Sum of Cubes Algebraic Identity

The key to solving this problem efficiently is the algebraic identity for the sum of two cubes:

$$ a^3 + b^3 = (a+b)(a^2 - ab + b^2) $$

Let's compare this identity to our given expression. We can set:

  • $a = 885$
  • $b = 115$

Now, let's rewrite the expression using $a$ and $b$:

$$ \text{Expression} = \frac{a^3 + b^3}{a^2 + b^2 - ab} $$

Applying the Identity for Simplification

We can substitute the factored form of $a^3 + b^3$ into our expression:

$$ \text{Expression} = \frac{(a+b)(a^2 - ab + b^2)}{a^2 + b^2 - ab} $$

Notice that the term $(a^2 - ab + b^2)$ appears in both the numerator and the denominator. Since $a=885$ and $b=115$, neither $a$ nor $b$ is zero, and the denominator $(a^2 + b^2 - ab)$ will not be zero. Therefore, we can cancel out this common term:

$$ \text{Expression} = a+b $$

Calculating the Final Result

Now, the problem simplifies to just adding the values of $a$ and $b$:

$$ \text{Result} = 885 + 115 $$

$$ \text{Result} = 1000 $$

Thus, the value of the given expression is 1000.

Was this answer helpful?

Similar Questions

  1. \(\sqrt{\frac{?}{196}}=\frac{72}{56}\)
  2. \(\frac{\sqrt{5}-\sqrt{3}}{\sqrt{5}+\sqrt{3}}\) is equal to
  3. \(\sqrt{\frac{36.1}{102.4}}\) = ?
  4. \(\sqrt{9-4\sqrt{5}}=\)
  5. \(\sqrt{29.8116}+\sqrt{77.44}=\)
  6. \(\frac{(0.05)^2+(0.41)^2+(0.073)^2}{(0.005)^2+(0.041)^2+(0.0073)^2}=\)
  7. \(\sqrt{9+4\sqrt{5}} \) =
  8. \(\sqrt{12.0409}-\sqrt{1.2544}\) =?
  9. If \(\sqrt{\left(1+\frac{27}{169}\right)} = \left(1+\frac{x}{13}\right) \) , then the value of x is:


Important Questions from Surds and Indices

  1. Find the cube root of 78402752

  2. What is the least number which, when multiplied by 28, forms a perfect square?

  3. Find the value of :

    [(3 × 3 × 3 × 3 × 3 × 3) 6 ÷ (3 × 3 × 3 × 3) 7 × 3 4]

  4. The cube root of - 64 × - 1331 is:

  5. If \(\sqrt{4624}=68\) , then the value of:

    \(\sqrt{46.24}+\sqrt{0.4624}+\sqrt{0.004624}\)

Need Expert Advice?
Upcoming Exams
SSC JHT
September 08, 2026
SSC Stenographer
September 09, 2026
SSC Selection Post
September 16, 2026
Test Series
UPSSSC PET img
State Exams
UPSSSC PET 2025 Mock Test Series (250+ Tests)
420 Tests 23 Tests Free
9409 Attempts
4.3(148)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App