arrow
arrow
arrow
If a=28−512a = 28 - 5\sqrt{12}a=28−512​ and b=2+3b = 2 + \sqrt{3}b=2+3​​, find the value of (a3+b)(a\sqrt{3} + b)(a3​+b)​​
Question

If a=28512a = 28 - 5\sqrt{12} and b=2+3b = 2 + \sqrt{3}​, find the value of (a3+b)(a\sqrt{3} + b)​​

A.

318331-8\sqrt{3}​​

B.

32+27332 + 27\sqrt3​​

C.

30+303-30 + 30\sqrt3​​

D.

28+293-28 + 29\sqrt3​​

Correct option is D

Given:

a = 2851228 - 5\sqrt{12}​​​

b = 2+32 + \sqrt{3}​​​

Solution:

Simplify a:

a=28512=285×23=28103a = 28 - 5\sqrt{12} = 28 - 5 \times 2\sqrt{3} = 28 - 10\sqrt{3}​​

Now, calculate a3:a\sqrt{3}​:​​

a3=(28103)3=28310×3=28330a\sqrt{3} = (28 - 10\sqrt{3})\sqrt{3} = 28\sqrt{3} - 10 \times 3 = 28\sqrt{3} – 30​​

Simplify b:

b=2+3b = 2 + \sqrt{3}​​

Now, compute a3+b:a\sqrt{3} + b:​​

a3+b=(28330)+(2+3)=28330+2+3a\sqrt{3} + b = (28\sqrt{3} - 30) + (2 + \sqrt{3}) = 28\sqrt{3} - 30 + 2 + \sqrt{3}​​

a3+b=283+330+2=29328a\sqrt{3} + b = 28\sqrt{3} + \sqrt{3} - 30 + 2 = 29\sqrt{3} - 28​​

Free Tests

Free
Must Attempt

CBT-1 Full Mock Test 1

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

RRB NTPC Graduate Level PYP (Held on 5 Jun 2025 S1)

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

CBT-1 General Awareness Section Test 1

languageIcon English
  • pdpQsnIcon40 Questions
  • pdpsheetsIcon30 Marks
  • timerIcon25 Mins
languageIcon English

Similar Questions

test-prime-package

Access ‘RRB Group D’ Mock Tests with

  • 60000+ Mocks and Previous Year Papers
  • Unlimited Re-Attempts
  • Personalised Report Card
  • 500% Refund on Final Selection
  • Largest Community
students-icon
354k+ students have already unlocked exclusive benefits with Test Prime!
Our Plans
Monthsup-arrow