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\(S=1+5+9+....+2005+2009\)

\(taco:S=\frac{\left[\left(2009-1\right):4+1\right].\left(2009+1\right)}{2}\)

\(S=\frac{503.2010}{2}\)

\(S=505515\)

505515

ket

ban

nha

1 . what about going swimming?

2 . how tall is the Mount Everest ?

Let's go swimming.

=> What about going swimming ?

What's the height of the Mount Everest ?

=> How tall is the Mount Everest ?

2² . x + 2^y = 2013

=> 4 . x + 4 = 2013

=> 4x = 2009

=> x = 502,25

y = 2 nữa nhé mik bị thiếu

a)\(\left(x-18\right)=\frac{75}{25}\)

\(x-18=3\)

\(x=21\)

b) \(\left(27x+6\right):3.11=9\)

\(\left(27x+6\right):3=\frac{9}{11}\)

\(\left(27x+6\right)=\frac{27}{11}\)

\(27x=\frac{27}{11}-6=-\frac{39}{11}\)

\(x=-\frac{39}{11}:27=-\frac{39}{297}=-\frac{13}{99}\)

c) \(\left(15-6x\right).3^5=3^6\)

\(15-6x=3^6:3^5=3\)

\(15-3=6x\)

\(12=6x=>x=2\)

\(3^2.\left(3x-2\right)=2^3\)

\(9.\left(3x-2\right)=8\)

\(27x-18=8\)

\(27x=26\)

\(x=\frac{26}{27}\)

\(3^2.\left(3x-2\right)=2^3\)

\(\Rightarrow\) \(9.\left(3x-2\right)=8\)

\(\Rightarrow\) \(3x-2=\frac{8}{9}\)

\(\Rightarrow\) \(3x=\frac{26}{9}\)

\(\Rightarrow\) \(x=\frac{26}{27}\)

2^3 = 8

\(2^3=8\)

\(3x-3+8=14\)

\(3x-3=14-8\)

\(3x-3=6\)

\(3x=6+3\)

\(3x=9\)

\(x=9:3\)

\(x=3\)

\(1+4+4^2+4^3+.....+4^{2018}\)

\(=\left(1+4+4^2\right)+\left(4^3+4^4+4^5\right)+....+\left(4^{2016}+4^{2017}+4^{2018}\right)\)

\(=21+\left[4^3\left(1+4+4^2\right)\right]+....+\left[4^{2016}\left(1+4+4^2\right)\right]\)

\(=21+4^3\cdot21+....+4^{2016}\cdot21\)

\(=21\left(1+4^3+....+4^{2016}\right)\)

\(\Rightarrowđpcm\)

(3x-2)mũ 3=294+7

(3x-2)mũ 3=301=.......

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