\(62,9\div17=3,7\)

\(2,1\div0,56=3,75\)

\(9\div3,6=2,5\)

\(0,51\div0,5=1,02\)

ai trên 11đ thì tk mk nhé ^^ thanks

62,9: 17= 3,7.

2,1: 0,56= 3,75.

9: 3,6= 2,5.

0,51: 0,5= 1,02.

a, 0,5 < x < 0,6

=> x =0,51 

b, 0,51 > x >0,5

=> x =5,02

a:0,51;0,52;0,52

b:0,511;0,512;0,513

a) Ta có: \(\left(-2.5\cdot0.38\cdot0.4\right)-\left[0.125\cdot3.15\cdot\left(-8\right)\right]\)

\(=\left(-1\cdot0.38\right)-\left[-1\cdot3.15\right]\)

\(=-0.38+3.15\)

\(=\dfrac{277}{100}\)

b) Ta có: \(\left[\left(-20.83\right)\cdot0.2+\left(-9.17\right)\cdot0.2\right]:\left[2.47\cdot0.5-\left(-3.53\right)\cdot0.51\right]\)

\(=\dfrac{0.2\left(-20.83-9.17\right)}{3.0353}\)

\(=\dfrac{0.2\cdot\left(-30\right)}{3.0353}=\dfrac{-60000}{30353}\)

b. \(\dfrac{45}{100}:3-\dfrac{24,5}{100}:5\)

=\(0,45:3-0,245:5\)

= 0,15 - 0,049

= 0,101

c. 0,56 - \(\dfrac{12}{100}\)+ \(\dfrac{3}{4}-1\)

= 0,56 - 0,12 + 0,75 - 1

= 0,19

d. ( 0,4 x 7 - \(\dfrac{140}{100}\):0,5) x \(\left(\dfrac{2}{100}+\dfrac{4}{100}+\dfrac{6}{100}+...+1\right)\)

= (2,8 - 2,8 ) x (0,02 + 0,04 +0,06 +...+1)

=0

Không có câu A nha!

\(n_K=\dfrac{7.8}{39}=0.2\left(mol\right)\)

\(K+H_2O\rightarrow KOH+\dfrac{1}{2}H_2\)

\(V_{H_2}=0.1\cdot22.4=2.24\left(l\right)\)

PTHH: \(K+H_2O\rightarrow KOH+\dfrac{1}{2}H_2\uparrow\)

Ta có: \(n_{H_2}=\dfrac{1}{2}n_K=\dfrac{1}{2}\cdot\dfrac{7,8}{39}=0,1\left(mol\right)\)

\(\Rightarrow V_{H_2}=0,1\cdot22,4=2,24\left(l\right)\)