a: \(y:\dfrac{2}{3}=-\dfrac{7}{2}+\dfrac{3}{5}=\dfrac{-35+6}{10}=\dfrac{-29}{10}\)
nên \(y=-\dfrac{29}{10}\cdot\dfrac{2}{3}=\dfrac{-58}{30}=-\dfrac{29}{15}\)
b: \(\dfrac{y}{-7}=-\dfrac{20}{35}\)
nên y/7=20/35
hay y=4
c: \(\dfrac{4}{5}=\dfrac{36}{-y}\)
nên \(y=-36\cdot\dfrac{5}{4}=-45\)
Bài 1: tìm các số x,y,z
a,\(\dfrac{x}{4}\)=\(\dfrac{y}{3}\)=\(\dfrac{z}{9}\)và x-3y+4z=62
b,\(\dfrac{x}{y}\)=\(\dfrac{9}{7}\);\(\dfrac{y}{z}\)=\(\dfrac{7}{3}\)và x-y+z=-15
c,\(\dfrac{x}{y}\)=\(\dfrac{7}{20}\);\(\dfrac{y}{z}=\dfrac{7}{3}\) và 2x+5y-2z=100
bài 2 tìm các số x,y,z
a,5x=8y=20z và x-y-z=3
b,\(\dfrac{6}{11}\)x=\(\dfrac{9}{2}y\)=\(\dfrac{18}{5}z\) và -x+y+z=-120
bài 3:tìm x,y,z biết
a,\(\dfrac{x}{12}\)=\(\dfrac{y}{9}=\dfrac{z}{5}\)và xyz=20
b,\(\dfrac{x}{5}=\dfrac{y}{7}=\dfrac{z}{3}\)và x2 + y2 -z2 =585
Tìm x \(\in\) Z biết;
a) \(\dfrac{x}{15}=\dfrac{4}{y}=\dfrac{-2}{5}\)
b) \(\dfrac{x-3}{4}=\dfrac{15}{20}\)
c) \(\dfrac{-5}{9}+\dfrac{-8}{15}+\dfrac{22}{-9}+\dfrac{-7}{15}< x\le\dfrac{-1}{3}+\dfrac{-1}{4}+\dfrac{-5}{12}\)
bài 1 tìm x,y,z
a, \(\dfrac{x}{10}\)=\(\dfrac{y}{15}\),x=\(\dfrac{7}{2}\) và x +2y-3z=20
b,2x=3y,49=57 và 4x-3y+5z=7
c, \(\dfrac{2x}{3}\)=\(\dfrac{3y}{4}\)=\(\dfrac{47}{5}\) và x+y+z=49
bài 2 tìm x trong tỉ lệ thức sau
a, \(\dfrac{x-3}{x+5}=\dfrac{5}{7}\)
b,\(\dfrac{7}{x-1}\) =\(\dfrac{x+1}{9}\)
c,\(\dfrac{x+4}{20}=\dfrac{2}{x+4}\)
d,\(\dfrac{x-1}{x+2}=\dfrac{x-2}{x+3}\)
Bài 1: tìm các số x,y,z
a,\(\dfrac{x}{4}=\dfrac{7}{3}=\dfrac{z}{9}\) và x-3y+4z=62
b,\(\dfrac{x}{y}=\dfrac{9}{7}\);\(\dfrac{y}{z}=\dfrac{7}{3}\)và x-y+z=-15
c,\(\dfrac{x}{y}=\dfrac{7}{20}\);\(\dfrac{y}{x}=\dfrac{7}{3}\)và 2x+5y-2z=100
Tìm x, biết :
a) \(\left(\dfrac{31}{20}-\dfrac{26}{45}\right).\dfrac{-36}{35}< x< \left(\dfrac{51}{56}+\dfrac{8}{21}+\dfrac{1}{3}\right).\dfrac{8}{13}\)
b) \(\dfrac{-3}{5}.x=\dfrac{1}{4}+0,75\)
c) \(\left(\dfrac{1}{7}-\dfrac{1}{3}\right).x=\dfrac{28}{3}.\left(\dfrac{1}{4}-\dfrac{1}{7}\right)\)
d) \(\dfrac{5}{7}.x=\dfrac{9}{8}-0,125\)
e)\(\left(\dfrac{2}{11}+\dfrac{1}{3}\right).x=\left(\dfrac{1}{7}-\dfrac{1}{8}\right).56\)
Thực hiện phép tính
a) \(\dfrac{1}{2}.\left(\dfrac{2}{9}+\dfrac{3}{7}-\dfrac{5}{27}\right)\) b) \(\left(\dfrac{-5}{28}+1,75+\dfrac{8}{35}\right):\left(-3\dfrac{9}{20}\right)\)
c) \(\dfrac{1}{3}.\dfrac{5}{7}-\dfrac{7}{27}.\dfrac{36}{14}\) d) \(70,5-528:\dfrac{15}{2}\)
Làm đúng nhận tick!
1. Tính hợp lý giá trị các biểu thức sau:
A= \(49\dfrac{8}{23}\)\(-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)
B= \(6\dfrac{3}{8}+5\dfrac{1}{2}\)
C= \(8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)\)
2. Tìm x, biết
a) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
b) \(x:4\dfrac{1}{3}=-2,5\)
c) \(x:\dfrac{-3}{5}=\dfrac{-10}{21}\)
d) \(\dfrac{2}{3}.x-\dfrac{1}{2}=\dfrac{1}{10}\)
e) \(\dfrac{1}{2}.x+\dfrac{1}{2}=\dfrac{5}{2}\)
g) \(\dfrac{-2}{3}-\dfrac{1}{3}.\left(2.x-5\right)=\dfrac{3}{2}\)
h) \(\dfrac{2}{5}.x+\dfrac{1}{2}=\dfrac{-3}{4}\)
i) \(\left(2.x-2\dfrac{4}{5}\right):3\dfrac{1}{8}=1\dfrac{3}{5}\)
k) \(3,2x-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):3\dfrac{2}{3}=\dfrac{7}{20}\)
j) \(\dfrac{2}{3}.x-\dfrac{3}{7}.\left(1-x\right)=\dfrac{20}{7}\)
Làm đúng nhận tick như đã nói! Hãy thể hiện trí thông minh và yêu thích bộ môn toán của mình
bài 1 : so sánh :
a) \(\dfrac{23}{21}\)và\(\dfrac{21}{23}\)
b)\(\dfrac{19}{26}\)và \(\dfrac{21}{25}\)
bài 2 : sắp sếp các phân số sau từ bé đến lớn :
a)\(\dfrac{7}{36};\dfrac{24}{36};\dfrac{13}{36};\dfrac{1}{36};\dfrac{43}{36};\dfrac{36}{36}\)
b)\(\dfrac{-3}{10};\dfrac{-31}{100};\dfrac{-297}{1000};\dfrac{10000}{-3056}\)
c)\(\dfrac{13}{20};\dfrac{7}{20};\dfrac{9}{4};\dfrac{2}{5};\dfrac{1}{2}\)
d)\(\dfrac{13}{21};\dfrac{152}{17};\dfrac{13}{17};\dfrac{-5}{21}\)
e)\(\dfrac{-1}{2};\dfrac{3}{-4};\dfrac{-2}{3};\dfrac{4}{-5}\)
Cho C= \(4+\dfrac{1}{7^6}+\dfrac{3}{7}+\dfrac{4}{7^2}+\dfrac{-441}{7^6}+\dfrac{27}{7^5}\)
D= \(\dfrac{147}{7^3}+4+\dfrac{35}{7^7}+\dfrac{4}{7^2}+\dfrac{27}{7^5}+\dfrac{-9}{7^9}\)
So sánh C với D
