là sao vậy ak

ko rõ lắm 

\(\frac{x}{12}-\frac{x}{15}=\frac{1}{6}\)

\(\Leftrightarrow\frac{5x}{60}-\frac{4x}{60}=\frac{10}{60}\)

\(\Leftrightarrow5x-4x=10\)

\(\Leftrightarrow x=10\)

Ta có : \(\frac{x}{12}-\frac{x}{15}=\frac{1}{6}\)

=> \(\frac{15x}{12.15}-\frac{12x}{12.15}=\frac{1}{6}\)

=> \(\frac{15x-12x}{180}=\frac{1}{6}\)

=> \(\frac{3x}{180}=\frac{1}{6}\)

=> \(\frac{x}{60}=\frac{1}{6}\)

=> \(6x=60\)

=>    \(x=60:6\)

=>    \(x=10\)

B=1/25.27+1/27.29+1/29.31+.......+1/73.75

=1/25+1/75

=3/75+1/75

=4/75.

#)Giải :

\(B=\frac{1}{25.27}+\frac{1}{27.29}+...+\frac{1}{73.75}\)

\(2B=\frac{2}{25.27}+\frac{2}{27.29}+...+\frac{2}{73.75}\)

\(2B=\frac{1}{25}-\frac{1}{27}+\frac{1}{27}-\frac{1}{29}+...+\frac{1}{73}-\frac{1}{75}\)

\(2B=\frac{1}{25}-\frac{1}{75}\)

\(2B=\frac{2}{75}\)

\(B=\frac{2}{75}\div2\)

\(B=\frac{1}{75}\)

Mọi người giải chi tiết giúp mình

\(\frac{1}{3-\sqrt{7}}-\frac{1}{3+\sqrt{7}}\)

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

\(=\frac{3+\sqrt{7}-3+\sqrt{7}}{9-7}\)

\(=\frac{2\sqrt{7}}{2}\)

\(=\sqrt{7}\)

phần B là gì cơ?

mình biết làm câu D thôi còn câu còn lại chắc bạn ghi sai đề

\(D=\frac{4^7.2^8}{3.2^{15}.16^2-5.2^2.\left(2^{10}\right)^2}=\frac{2^{14}.2^8}{3.2^{15}.\left(2^4\right)^2-5.2^2.2^{20}}=\frac{2^{22}}{3.2^{15}.2^8-5.2^22^{20}}=\frac{2^{22}}{3.2^{22}.2-5.2^{22}}\)

\(=\frac{2^{22}}{2^{22}\left(3.2-5\right)}=\frac{2^{22}}{2^{22}.1}=1\) bạn ơi dấu . là nhân nhé

Nhân cả 2 vế với 2 ta có:

2P=24(5²+1)(5⁴+1)(5⁸+1)(5¹⁶+1)

2P=(5²-1)(5²+1)(5⁴+1)(5⁸+1)(5¹⁶+1)

2P=(5⁴-1)(5⁴+1)(5⁸+1)(5¹⁶+1)

2P=(5⁸-1)(5⁸+1)(5¹⁶+1)

2P=(5¹⁶-1)(5¹⁶+1)

2P=5³²-1

P=\(\frac{5^{32}-1}{2}\)
 

\(P=12\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(2P=\left(5^2-1\right)\left(5^2+1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(2P=\left(5^4-1\right)\left(5^4+1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(2P=\left(5^8-1\right)\left(5^8+1\right)\left(5^{16}+1\right)\)

\(2P=\left(5^{16}-1\right)\left(5^{16}+1\right)\)

\(2P=5^{32}-1\)

\(\Rightarrow P=\frac{5^{32}-1}{2}\)

1, CÓ( X+1,5)⁸ VÀ (2,7 -Y)¹²> HOẶC = 0

         MÀ (X+1,5)⁸ + (2,7-Y)¹²  =0

    SUY RA   \(\hept{\begin{cases}X+1,5=0\\2,7-Y=0\end{cases}}\)

      SUY RA\(\hept{\begin{cases}X=-1,5\\Y=2,7\end{cases}}\)

de ghe de cho nam ngaN

bạn ko làm thì thôi , ko cần bạn nói vậy