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14 (a) Work out the value of \( \left( \frac{16}{81} \right)^{\frac{3}{2}} \) (b) Work out the value of \( a + b + c \) 3$^{-1}$ = 1/9 3$^{3}$ = 9$ adical{3}$ 3$^{\frac{3}{2}}$ = 1/$ adical{3}$ - Edexcel - GCSE Maths - Question 15 - 2018 - Paper 1

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14-(a)-Work-out-the-value-of---\(-\left(-\frac{16}{81}-\right)^{\frac{3}{2}}-\)----(b)-Work-out-the-value-of---\(-a-+-b-+-c-\)----3$^{-1}$-=-1/9---3$^{3}$-=-9$-adical{3}$---3$^{\frac{3}{2}}$-=-1/$-adical{3}$-Edexcel-GCSE Maths-Question 15-2018-Paper 1.png

14 (a) Work out the value of \( \left( \frac{16}{81} \right)^{\frac{3}{2}} \) (b) Work out the value of \( a + b + c \) 3$^{-1}$ = 1/9 3$^{3}$ = 9$ adica... show full transcript

Worked Solution & Example Answer:14 (a) Work out the value of \( \left( \frac{16}{81} \right)^{\frac{3}{2}} \) (b) Work out the value of \( a + b + c \) 3$^{-1}$ = 1/9 3$^{3}$ = 9$ adical{3}$ 3$^{\frac{3}{2}}$ = 1/$ adical{3}$ - Edexcel - GCSE Maths - Question 15 - 2018 - Paper 1

Step 1

Work out the value of \( \left( \frac{16}{81} \right)^{\frac{3}{2}} \)

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Answer

To solve ( \left( \frac{16}{81} \right)^{\frac{3}{2}} ), we start by rewriting it in terms of square roots:

(1681)32=(1681)3\left( \frac{16}{81} \right)^{\frac{3}{2}} = \left( \sqrt{\frac{16}{81}} \right)^{3}

Calculating the square root first:

1681=1681=49\sqrt{\frac{16}{81}} = \frac{\sqrt{16}}{\sqrt{81}} = \frac{4}{9}

Now raising this result to the power of 3:

(49)3=4393=64729\left( \frac{4}{9} \right)^{3} = \frac{4^{3}}{9^{3}} = \frac{64}{729}

Thus, ( \left( \frac{16}{81} \right)^{\frac{3}{2}} = \frac{64}{729} ).

Step 2

Work out the value of \( a + b + c \)

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Answer

From the equations given, let's express each in terms of powers of 3:

  1. For ( 3^{-1} = \frac{1}{9} ), we can write ( \frac{1}{9} = 3^{-2} ).
  2. For ( 3^{3} = 9 \sqrt{3} ), this can be rewritten as ( 9 \sqrt{3} = 3^{2} \cdot 3^{\frac{1}{2}} = 3^{2.5} = 3^{\frac{5}{2}} ).
  3. Finally, for ( 3^{\frac{3}{2}} = \frac{1}{\sqrt{3}} ), we know this rewrites as ( 3^{\frac{3}{2}} = 3^{1.5} ).

So we rewrite the addition:

a+b+c=32+352+31.5a + b + c = 3^{-2} + 3^{\frac{5}{2}} + 3^{1.5}

Without specific values for ( a, b, c ), we cannot compute a numerical value, but we confirm they are in terms of powers of 3.

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