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    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​​

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