3√2 - 5√18 + 6√72 - 4√98 = 3√2-5.3√2+6.2.3√2-4.7/3.3√2

                                          = 3√2(1-5+12-28/3)
                                          = 3√2.(-4/3)
                                          = -4√2

√20 - √45 + 3√18 + √72

= √4.5 - √9.5 + 3√9.2 + √36.2

= 2√5 - 3√5 + 9√2 + 6√2

= -√5 + 15√2

a,M=2^0-2^1+2^2-2^3+2^4-2^5+.....+2^2012

2M=2^1-2^2+2^3-2^4+2^5-2^5+......-2^2012+2^2013

3M=2^0+2^2013

M=(2^0+2^2013)÷3

Vậy.......

b,N=3-3^2+3^3-3^4+3^5-3^6+.....+3^2011-3^2012

3N=3^2-3^3+3^4-3^5+3^6-3^7+......+3^2012-3^2013

4N=3-3^2013

N=(3-3^2013)÷4

Vậy........

K tao nhé ko lên lớp tao đánh m😈😈😈

Bt dễ thế mà ko làm dc😂😂😂😂😂

phần c đâu

P=1+5²+5⁴+5⁶+...+5⁹⁸

=>5².P=P=5²+5⁴+5⁶+...+5⁹⁸+5¹⁰⁰

=>25P-P=24P=P=5²+5⁴+5⁶+...+5⁹⁸+5¹⁰⁰-(1+5²+5⁴+5⁶+...+5⁹⁸)

=>24P=5¹⁰⁰-1

=>P=\(\frac{5^{100}-1}{24}.\)

2) \(\sqrt{98}-\sqrt{72}+0,5\sqrt{8}\)

\(=7\sqrt{2}-6\sqrt{2}+\sqrt{2}\)

\(=\left(7-6+1\right)\sqrt{2}\)

\(=2\sqrt{2}\)

3) \(\sqrt{9a}-\sqrt{16a}+\sqrt{49a}\)

\(=3\sqrt{a}-4\sqrt{a}+7\sqrt{a}\)

\(=\left(3-4+7\right)\sqrt{a}\)

\(=6\sqrt{a}\)

4) \(\sqrt{16b}+2\sqrt{40b}-3\sqrt{90b}\)

\(=4\sqrt{b}+4\sqrt{10b}-9\sqrt{10b}\)

\(=4\sqrt{b}-5\sqrt{10b}\)

Gấp nha 

1. 2^36.2^45=2^81

2. 2^30.5^30=10^30

\(4^{18}.8^{15}=\left(2^2\right)^{18}.\left(2^3\right)^{15}\)

\(=2^{36}.2^{45}\)

\(=2^{81}\)

\(4^{15}.5^{30}=\left(2^2\right)^{15}.5^{30}\)

\(=2^{30}.5^{30}\)

\(=\left(2.5\right)^{30}\)

\(=10^{30}\)

\(\frac{3.72^2.54^2}{108^4}=\frac{3.\left(3^2.2^3\right)^2.\left(3^3.2\right)^2}{\left(3^3.2^2\right)^4}\)

\(=\frac{3.3^4.2^6.3^6.2^2}{3^{12}.2^8}\)

\(=\frac{3^{11}.2^8}{3^{12}.2^8}\)

\(=\frac{1}{3}\)

1) \(4^{18}.8^{15}=\left(2^2\right)^{10}.\left(2^3\right)^{15}=2^{20}.2^{45}=2^{65}\)

2) \(4^{15}.5^{30}=\left(2^2\right)^{15}.5^{30}=2^{30}.5^{30}=10^{30}\)

3) \(\frac{72^3.54^2}{108^4}=\frac{\left(2^3.3^2\right)^3.\left(2.3^3\right)^2}{\left(2^2.3^3\right)^4}=\frac{\left(2^3\right)^3.\left(3^2\right)^3.2^2.\left(3^3\right)^2}{\left(2^2\right)^4.\left(3^3\right)^4}\)

\(=\frac{2^9.3^6.2^2.3^6}{2^8.3^{12}}=\frac{2^{11}.3^{12}}{2^8.3^{12}}=2^3=8\)

Bài 1:

a: \(\sqrt{50}+2\sqrt{8}-\dfrac{3}{2}\cdot\sqrt{72}+\sqrt{125}\)

\(=5\sqrt{2}+2\cdot2\sqrt{2}-\dfrac{3}{2}\cdot6\sqrt{2}+\sqrt{125}\)

\(=9\sqrt{2}-9\sqrt{2}+5\sqrt{5}=5\sqrt{5}\)

b: \(\left(3\sqrt{2}-\sqrt{5}\right)^2-\dfrac{9}{\sqrt{5}-\sqrt{2}}\)

\(=18-2\cdot3\sqrt{2}\cdot\sqrt{5}+5-\dfrac{9\left(\sqrt{5}+\sqrt{2}\right)}{5-2}\)

\(=23-6\sqrt{10}-3\left(\sqrt{5}+\sqrt{2}\right)\)

\(=23-6\sqrt{10}-3\sqrt{5}-3\sqrt{2}\)

c: \(5\sqrt{4a}-3\sqrt{25a}+\sqrt{9a}\)

\(=5\cdot2\sqrt{a}-3\cdot5\sqrt{a}+3\sqrt{a}\)

\(=10\sqrt{a}-15\sqrt{a}+3\sqrt{a}=-2\sqrt{a}\)

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