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

Evaluate √(19 - 6√10) + 3

This question was previously asked in
UPTET 2026 Paper 2 Social Studies Question Paper (3-Jul-2026) (Shift 1)
The correct answer is

√10

We need to express \(19 - 6\sqrt{10}\) in the form \(a + b - 2\sqrt{ab}\), which is \((\sqrt{a} - \sqrt{b})^2\).

We need \(a + b = 19\) and \(2\sqrt{ab} = 6\sqrt{10} \Rightarrow ab = 90\).

Solving \(a+b=19\) and \(ab=90\), the values are \(a = 10\) and \(b = 9\).

So, \(19 - 6\sqrt{10} = (\sqrt{10} - \sqrt{9})^2 = (\sqrt{10} - 3)^2\).

Since \(\sqrt{10} \approx 3.16 > 3\), \(\sqrt{19 - 6\sqrt{10}} = \sqrt{10} - 3\).

Therefore, \(\sqrt{19-6\sqrt{10}} + 3 = (\sqrt{10} - 3) + 3 = \sqrt{10}\).

Was this answer helpful?

Similar Questions

  1. If 27(x/3) = 9, find x.

  2. Simplify the following expression:  

    \[ \left(\frac{x^2}{x^m}\right)^{1+m} \left(\frac{x^m}{x^n}\right)^{m+n} \left(\frac{x^n}{x^l}\right)^{n+l} \]

  3. If 2ˣ = 4ˣ⁻¹, find x.

  4. What is the cube root of 1728?


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 (27) m = (81) n, then m 2: mn = ?

Need Expert Advice?
Test Series
UP TET img
Teaching
UPTET 2026 (Paper 1 & 2) Mock Test Series
257 Tests 16 Tests Free
2136 Attempts
4.6(18)
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