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Mathematics

Write down the values of :

(i) (23)2(2\sqrt{3})^2

(ii) (322)2\Big(\dfrac{3}{2}\sqrt{2}\Big)^2

(iii) (5+3)2(5 + \sqrt{3})^2

(iv) (63)2(\sqrt{6} - 3)^2

(v) (3+25)2(3 + 2\sqrt{5})^2

(vi) (5+6)2(\sqrt{5} + \sqrt{6})^2

(vii) (322)2\Big(\dfrac{3}{2\sqrt{2}}\Big)^2

(viii) (563)2(5 - 6\sqrt{3})^2

Rational Irrational Nos

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Answer

(i) Solving,

(23)2\Rightarrow (2\sqrt{3})^2

23×23\Rightarrow 2\sqrt{3} \times 2\sqrt{3}

⇒ 4 × 3

⇒ 12.

Hence, (23)2(2\sqrt{3})^2 = 12.

(ii) Solving,

(322)2322×32294×292.\Rightarrow \Big(\dfrac{3}{2}\sqrt{2}\Big)^2 \\[1em] \Rightarrow \dfrac{3}{2}\sqrt{2} \times \dfrac{3}{2}\sqrt{2} \\[1em] \Rightarrow \dfrac{9}{4} \times 2 \\[1em] \Rightarrow \dfrac{9}{2}.

Hence, (322)2=92\Big(\dfrac{3}{2}\sqrt{2}\Big)^2 = \dfrac{9}{2}.

(iii) Solving,

(5+3)2(5)2+(3)2+2×5×325+3+10328+103\Rightarrow (5 + \sqrt{3})^2 \\[1em] \Rightarrow (5)^2 + (\sqrt{3})^2 + 2 \times 5 \times \sqrt{3} \\[1em] \Rightarrow 25 + 3 + 10\sqrt{3} \\[1em] \Rightarrow 28 + 10\sqrt{3}

Hence, (5+3)2=28+103(5 + \sqrt{3})^2 = 28 + 10\sqrt{3}.

(iv) Solving,

(63)2(6)2+(3)22×3×66+9661566\Rightarrow (\sqrt{6} - 3)^2 \\[1em] \Rightarrow (\sqrt{6})^2 + (3)^2 - 2 \times 3 \times \sqrt{6} \\[1em] \Rightarrow 6 + 9 - 6\sqrt{6} \\[1em] \Rightarrow 15 - 6\sqrt{6}

Hence, (63)2=1566(\sqrt{6} - 3)^2 = 15 - 6\sqrt{6}.

(v) Solving,

(3+25)2(3)2+(25)2+2×3×259+4×5+1259+20+12529+125\Rightarrow (3 + 2\sqrt{5})^2 \\[1em] \Rightarrow (3)^2 + (2\sqrt{5})^2 + 2 \times 3 \times 2\sqrt{5} \\[1em] \Rightarrow 9 + 4 \times 5 + 12\sqrt{5} \\[1em] \Rightarrow 9 + 20 + 12\sqrt{5} \\[1em] \Rightarrow 29 + 12\sqrt{5}

Hence, (3+25)2=29+125(3 + 2\sqrt{5})^2 = 29 + 12\sqrt{5}.

(vi) Solving,

(5+6)2(5)2+(6)2+2×5×65+6+23011+230\Rightarrow (\sqrt{5} + \sqrt{6})^2 \\[1em] \Rightarrow (\sqrt{5})^2 + (\sqrt{6})^2 + 2 \times \sqrt{5} \times \sqrt{6} \\[1em] \Rightarrow 5 + 6 + 2\sqrt{30} \\[1em] \Rightarrow 11 + 2\sqrt{30}

Hence, (5+6)2=11+230(\sqrt{5} + \sqrt{6})^2 = 11 + 2\sqrt{30}.

(vii) Solving,

(322)2322×32294×298\Rightarrow \Big(\dfrac{3}{2\sqrt{2}}\Big)^2 \\[1em] \Rightarrow \dfrac{3}{2\sqrt{2}} \times \dfrac{3}{2\sqrt{2}} \\[1em] \Rightarrow \dfrac{9}{4 \times 2} \\[1em] \Rightarrow \dfrac{9}{8}

Hence, (322)2=98\Big(\dfrac{3}{2\sqrt{2}}\Big)^2 = \dfrac{9}{8}.

(viii) Solving,

(563)2(5)2+(63)22×5×6325+108603133603\Rightarrow (5 - 6\sqrt{3})^2 \\[1em] \Rightarrow (5)^2 + (6\sqrt{3})^2 - 2 \times 5 \times 6\sqrt{3} \\[1em] \Rightarrow 25 + 108 - 60\sqrt{3} \\[1em] \Rightarrow 133 - 60\sqrt{3}

Hence, (563)2=133+603(5 - 6\sqrt{3})^2 = 133 + 60\sqrt{3}.

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