Các bạn giúp mình với mình đang cần gấp lắm

\(\frac{7}{3}.9-\frac{9}{4}.5+\frac{11}{5}.6-\frac{13}{6}.7+\frac{15}{7}.8-\frac{17}{8}.9+\frac{19}{9}.10\)

\(=21-\frac{45}{4}+\frac{66}{5}-\frac{91}{6}+\frac{120}{7}-\frac{153}{8}+\frac{190}{9}\)

\(=26,91230159\)

39/-90 - 7/2

x+\(\frac{1}{3}\)=\(\frac{2}{5}\)- (\(\frac{-1}{3}\))

x + \(\frac{1}{3}\)= \(\frac{2}{5}\)+\(\frac{1}{3}\)

x +1/3 =11/15

x= 11/15 -1/3

x= 2/5

b, 5/7-x=1/4 -(-3/5)

5/7 - x = 1/4 +3/5

5/7 - x =17/20

x = 5/7 -17/ 20

x= -19/140

1,

\(\frac{25}{12}+\left(\frac{-4}{12}\right)=\frac{7}{4}\)

\(\frac{-10}{8}+\frac{15}{4}=\frac{5}{2}\)

\(\frac{3}{8}+\frac{-14}{6}=\frac{-47}{24}\)

\(\frac{350}{150}+\left(\frac{-200}{360}\right)=\frac{16}{9}\)

\([\frac{5}{8}+\left(\frac{-3}{4}\right)]+\frac{15}{6}=\frac{-1}{8}+\frac{15}{6}=\frac{19}{8}\)

\(\frac{7}{3}+[\left(\frac{-5}{6}\right)+\left(\frac{-2}{3}\right)]=\frac{7}{3}+\left(\frac{-3}{2}\right)=\frac{5}{6}\)

4,

\(\frac{X+1}{5}=\frac{3}{7}\)

\(\Rightarrow\left(X-1\right).7=3.5\)

\(\Rightarrow7X-7=15\)

\(\Rightarrow7X=22\)

\(\Rightarrow X=\frac{22}{7}\)

\(\frac{X-3}{4}=\frac{1}{2}\)

\(\Rightarrow\left(X-3\right)2=1.4\)

\(\Rightarrow2X-6=4\)

\(\Rightarrow2X=10\)

\(\Rightarrow X=5\)

a) \(8^x:4^x=4\)

\(\Rightarrow\left(8:4\right)^x=4\)

\(\Rightarrow2^x=4\)

\(\Rightarrow2^x=2^2\)

\(\Rightarrow x=2\)

Vậy \(x=2.\)

b) \(\frac{-4,4}{9,9}=\frac{x}{1,89}\)

\(\Rightarrow x.9,9=\left(-4,4\right).1,89\)

\(\Rightarrow x.9,9=-8,316\)

\(\Rightarrow x=\left(-8,316\right):9,9\)

\(\Rightarrow x=-0,84\)

Vậy \(x=-0,84.\)

Chúc bạn học tốt!

8^x:4^x=4

(8:4)^x=4

2^x=4

2^x=2²

Vậy x=2

a) \(\frac{x+2015}{5}+\frac{x+2015}{6}=\frac{x+2015}{7}+\frac{x+2015}{8}\)

\(\frac{x+2015}{5}+\frac{x+2015}{6}-\frac{x+2015}{7}-\frac{x+2015}{8}=0\)

\(\left(x+2015\right).\left(\frac{1}{5}+\frac{1}{6}-\frac{1}{7}-\frac{1}{8}\right)=0\)

vì \(\frac{1}{5}+\frac{1}{6}-\frac{1}{7}-\frac{1}{8}\ne0\)

\(\Rightarrow\)x + 2015 = 0

\(\Rightarrow\)x = -2015

b) Tương tự

gõ đề bằng công thức toán nếu muốn đc trợ giúp tốt nhất

a, \(\dfrac{x-2}{5}=\dfrac{5}{7}\)

\(\Rightarrow7\left(x-2\right)=25\Rightarrow7x-14=25\)

\(\Rightarrow7x=39\Rightarrow x=\dfrac{39}{7}\)

b, \(\dfrac{-x-2}{3}=\dfrac{-6}{7}\)

\(\Rightarrow7\left(-x-2\right)=-18\Rightarrow-7x-14=-18\)

\(\Rightarrow-7x=-4\Rightarrow x=\dfrac{4}{7}\)

c, \(\dfrac{4}{7-x}=\dfrac{1}{3}\)

\(\Rightarrow12=7-x\Rightarrow7-x=12\)

\(\Rightarrow x=7-12=-5\)

Chúc bạn học tốt!!!