Giải VTH Toán 7 Luyện tập chung trang 23, 24 có đáp án

a) $2\text{x}+\frac{1}{2}=\frac{7}{9}$

$2\text{x}=\frac{7}{9}-\frac{1}{2}$

$2\text{x}=\frac{14}{18}-\frac{9}{18}$

$2\text{x}=\frac{5}{18}$

$\text{x}=\frac{5}{18}:2$

$\text{x}=\frac{5}{18}.\frac{1}{2}$

$\text{x}=\frac{5}{36}$

Vậy $\text{x}=\frac{5}{36}$

b) $\frac{3}{4}-6\text{x}=\frac{7}{13}$

$6\text{x}=\frac{3}{4}-\frac{7}{13}$

$6\text{x}=\frac{39}{52}-\frac{28}{52}$

$6\text{x}=\frac{11}{52}$

$\text{x}=\frac{11}{52}:6$

$\text{x}=\frac{11}{52}.\frac{1}{6}$

$\text{x}=\frac{11}{312}$

Vậy $\text{x}=\frac{11}{312}$

Ta có: 8,264.10$^{9}$ < 1,56.10$^{10}$ < 1,896.10$^{10}$ < 2,57.10$^{10}$ < 3,17.10$^{10}$ < 5,8.10$^{10}$ < 6,887.10$^{10}$ < 8,21.10$^{10}$ < 3,71.10$^{11}$.

Vậy thứ tự các hồ được sắp xếp như sau:

Nicaragua, Vostok, Ontario, Erie, Baikal, Michigan, Victoria, Superior, Caspian.

a) A = 32,125 – (6,325 + 12,125) – (37 + 13,675)

= 32,125 – 6,325 – 12,125 – 37 – 13,675

= (32,125 – 12,125) – (6,325 + 13,675) – 37

= 20 – 20 – 37

= –37

Vậy A = –37.

b) $B=4{,}75+{(\frac{-1}{2})}^{3}+0,{5}^{2}-3.\frac{-3}{8}$

$=4{,}75-\frac{1}{8}+0{,}25-\frac{-9}{8}$

$=(4{,}75+0{,}25)+(\frac{-1}{8}+\frac{9}{8})$

= 5 + 1

= 6.