là 59

a, (-0,2)2 $\times$ 5 - $\genfrac{}{}{0ex}{}{2^{13}\times 27^3}{4^6\times 9^5}$

= 0,04 $\times$ 5 - $\genfrac{}{}{0ex}{}{2^{13}\times 3^9}{2^{12}\times 3^{10}}$

= 0,2 - $\genfrac{}{}{0ex}{}{2}{3}$

= $\genfrac{}{}{0ex}{}{2}{10}$ - $\genfrac{}{}{0ex}{}{2}{3}$

=  - $\genfrac{}{}{0ex}{}{7}{15}$

b, $\genfrac{}{}{0ex}{}{5^6+2^2.25^3+2^3.125^2}{26.5^6}$

 = $\genfrac{}{}{0ex}{}{5^6+4.5^6+8.5^6}{26.5^6}$

= $\genfrac{}{}{0ex}{}{5^6.\left(1+4+8\right)}{26.5^6}$

= $\genfrac{}{}{0ex}{}{1}{2}$
 

Vì x chia hết cho cả 12, 15, 18 và 0<x<300

=> x thuộc BC(12,15,18)

Ta có : 12=22.3

            15=3.5

            18=2.32

=> BCNN(12,15,18)=22.32.5=180

=> BC(12,15,18)=B(180)={0;180;360;...}

Mà 0<x<360

=> x=180

Vậy x=180

1,Ha Long Bay is the north of vietnam.

2,it is about 170 km from hanoi.

3, we can get there and coach and  it takes about 3 hours.

4, it is about 2000 small islands and many famous caves.

5, the weather in the sea is beautiful.

6,The beach of Ha Long Bay is good for swimming

7.There are a lot of hotels and restaurants near the beach and an entertainment center on Tuan Chau island

4,75 - $x$ = $\genfrac{}{}{0ex}{}{2}{5}$ - $\genfrac{}{}{0ex}{}{3}{5}$

4,75 - $x$ = $\genfrac{}{}{0ex}{}{-1}{5}$

            $x$ = 4,75 + 0,2

              $x$ = 4,95

$x$ - $\genfrac{}{}{0ex}{}{4}{7}$ = $\genfrac{}{}{0ex}{}{5}{3}$

$x$        = $\genfrac{}{}{0ex}{}{5}{3}$ + $\genfrac{}{}{0ex}{}{4}{7}$

$x$        = $\genfrac{}{}{0ex}{}{47}{21}$