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Mathematics

Simplify and express each of the following as a rational number :

(i) (65)3×(52)2\Big(\dfrac{6}{5}\Big)^3 \times \Big(\dfrac{5}{2}\Big)^2

(ii) (34)2×(12)5×23\Big(\dfrac{3}{4}\Big)^2 \times \Big(\dfrac{-1}{2}\Big)^5 \times 2^3

(iii) (54)2×(23)2×(35)3\Big(\dfrac{5}{4}\Big)^2 \times \Big(\dfrac{2}{3}\Big)^2 \times \Big(\dfrac{-3}{5}\Big)^3

(iv) (34)3×(52)3×(23)5\Big(\dfrac{-3}{4}\Big)^3 \times \Big(\dfrac{-5}{2}\Big)^3 \times \Big(\dfrac{2}{3}\Big)^5

(v) (711)6÷(711)3\Big(\dfrac{7}{11}\Big)^6 ÷ \Big(\dfrac{7}{11}\Big)^3

(vi) (43)8÷(43)12\Big(\dfrac{-4}{3}\Big)^8 ÷ \Big(\dfrac{-4}{3}\Big)^{12}

Exponents

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Answer

(i) We have:

=(65)3×(52)2=6353×5222=63×5253×22=63×52322[Applying exponent law]=63×5122=6×6×65×2×2[51=15]=21620=545=1045\phantom{=} \Big(\dfrac{6}{5}\Big)^3 \times \Big(\dfrac{5}{2}\Big)^2 \\[1em] = \dfrac{6^3}{5^3} \times \dfrac{5^2}{2^2} \\[1em] = \dfrac{6^3 \times 5^2}{5^3 \times 2^2} \\[1em] = \dfrac{6^3 \times 5^{2-3}}{2^2}\quad \text{[Applying exponent law]} \\[1em] = \dfrac{6^3 \times 5^{-1}}{2^2} \\[1em] = \dfrac{6 \times 6 \times 6}{5 \times 2 \times 2} \quad {[5^{-1} = \dfrac{1}{5}]} \\[1em] = \dfrac{216}{20} \\[1em] = \dfrac{54}{5} = 10\dfrac{4}{5}

Hence, the answer is 104510\dfrac{4}{5}

(ii) We have:

=(34)2×(12)5×23=3242×(1)525×23=32×(1)5×2342×25=32×(1)5×23542[Applying exponent law]=32×(1)5×2242=(3×3)×(1)4×(4×4)[22=122=14]=964\phantom{=} \Big(\dfrac{3}{4}\Big)^2 \times \Big(\dfrac{-1}{2}\Big)^5 \times 2^3 \\[1em] = \dfrac{3^2}{4^2} \times \dfrac{(-1)^5}{2^5} \times 2^3 \\[1em] = \dfrac{3^2 \times (-1)^5 \times 2^3}{4^2 \times 2^5} \\[1em] = \dfrac{3^2 \times (-1)^5 \times 2^{3-5}}{4^2} \quad \text{[Applying exponent law]} \\[1em] = \dfrac{3^2 \times (-1)^5 \times 2^{-2}}{4^2} \\[1em] = \dfrac{(3 \times 3) \times (-1)}{4 \times (4 \times 4)} \quad [2^{-2} = \dfrac{1}{2^2} = \dfrac{1}{4}] \\[1em] = \dfrac{-9}{64}

Hence, the answer is 964\dfrac{-9}{64}

(iii) We have:

=(54)2×(23)2×(35)35242×2232×(3)353=52×22×(3)342×32×53=22×(3)32×52342[Applying exponent law]=22×(3)1×5142=(2×2)×(3)(4×4)×5[51=15]=1280=320\phantom{=} \Big(\dfrac{5}{4}\Big)^2 \times \Big(\dfrac{2}{3}\Big)^2 \times \Big(\dfrac{-3}{5}\Big)^3 \\[1em] \dfrac{5^2}{4^2} \times \dfrac{2^2}{3^2} \times \dfrac{(-3)^3}{5^3} \\[1em] = \dfrac{5^2 \times 2^2 \times (-3)^3}{4^2 \times 3^2 \times 5^3} \\[1em] = \dfrac{2^2 \times (-3)^{3-2} \times 5^{2-3}}{4^2} \quad \text{[Applying exponent law]} \\[1em] = \dfrac{2^2 \times (-3)^1 \times 5^{-1}}{4^2} \\[1em] = \dfrac{(2 \times 2) \times (-3)}{(4 \times 4) \times 5} \quad[5^{-1} = \dfrac{1}{5}] \\[1em] = \dfrac{-12}{80} = \dfrac{-3}{20}

Hence, the answer is 320\dfrac{-3}{20}

(iv) We have:

=(34)3×(52)3×(23)5=(3)343×(5)323×2535=(3)3×(5)3×2543×23×35=(3)3×(5)3×25343×35[Applying exponent law]=(3)3×(5)3×2243×35=(3×3×3)×(5×5×5)×(2×2)(4×4×4)×(3×3×3×3×3)=(27)×125×464×243=1×125×116×9[Dividing 27 and 243 by 27, 4 and 64 by 4]=125144\phantom{=} \Big(\dfrac{-3}{4}\Big)^3 \times \Big(\dfrac{-5}{2}\Big)^3 \times \Big(\dfrac{2}{3}\Big)^5 \\[1em] = \dfrac{(-3)^3}{4^3} \times \dfrac{(-5)^3}{2^3} \times \dfrac{2^5}{3^5} \\[1em] = \dfrac{(-3)^3 \times (-5)^3 \times 2^5}{4^3 \times 2^3 \times 3^5} \\[1em] = \dfrac{(-3)^3 \times (-5)^3 \times 2^{5-3}}{4^3 \times 3^5} \quad \text{[Applying exponent law]} \\[1em] = \dfrac{(-3)^3 \times (-5)^3 \times 2^2}{4^3 \times 3^5} \\[1em] = \dfrac{(-3 \times -3 \times -3) \times (-5 \times -5 \times -5) \times (2 \times 2)}{(4 \times 4 \times 4) \times (3 \times 3 \times 3 \times 3 \times 3)} \\[1em] = \dfrac{(-27) \times -125 \times 4}{64 \times 243} \\[1em] = \dfrac{-1 \times -125 \times 1}{16 \times 9} \quad \text{[Dividing 27 and 243 by 27, 4 and 64 by 4]} \\[1em] = \dfrac{125}{144} \\[1em]

Hence, the answer is 125144\dfrac{125}{144}

(v) We have:

=(711)6÷(711)3=(711)63[By division rule]=(711)3=73113=7×7×711×11×11=3431331\phantom{=} \Big(\dfrac{7}{11}\Big)^6 ÷ \Big(\dfrac{7}{11}\Big)^3 \\[1em] = \Big(\dfrac{7}{11}\Big)^{6-3} \quad \text{[By division rule]} \\[1em] = \Big(\dfrac{7}{11}\Big)^3 \\[1em] = \dfrac{7^3}{11^3} \\[1em] = \dfrac{7 \times 7 \times 7}{11 \times 11 \times 11} \\[1em] = \dfrac{343}{1331}

Hence, the answer is 3431331\dfrac{343}{1331}

(vi) We have:

=(43)8÷(43)12=(43)812[By division rule]=(43)4=(34)4[By reciprocal rule]=3×3×3×3(4)×(4)×(4)×(4)=81256\phantom{=} \Big(\dfrac{-4}{3}\Big)^8 ÷ \Big(\dfrac{-4}{3}\Big)^{12} \\[1em] = \Big(\dfrac{-4}{3}\Big)^{8-12} \quad \text{[By division rule]} \\[1em] = \Big(\dfrac{-4}{3}\Big)^{-4} \\[1em] = \Big(\dfrac{3}{-4}\Big)^{4} \quad \text{[By reciprocal rule]} \\[1em] = \dfrac{3 \times 3 \times 3 \times 3}{(-4) \times (-4) \times (-4) \times (-4)} \\[1em] = \dfrac{81}{256}

Hence, the answer is 81256\dfrac{81}{256}

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