x + 5/2 . x - 3/2 = 9/4

<=> x( 1+ 5/2 ) - 3/2 = 9/4

<=> x . 7/2      = 9/4 + 3/2

<=>   x .7/2     = 15/4

<=>  x              = 15/4 : 7/2

<=>    x            = 15/14

TA CÓ: 

X + 5/2 . X - 3/2 = 9/4

X + 5/2 .X = 9/4 +3/2 = 15/4 

(X . 1) + (5/2 . X) = 15/4

X . (1 + 5/2) =15/4

X . 7/2 = 15/4

X = (15/4) / (7/2)

X = 15/14

DỄ ÒM MÀ

BẠN HỌC TRỪNG NÀO MÀ MAI NỘP VẬY

mk hc thêm bn DTC CAO THU ơi

\(9^{1945}=9^{1944}.9=\left(9^2\right)^{972}.9=81^{972}.9\)

vì 81^972 có CSTC là 1=>9^1945 có CSTC là 9

\(2^{1930}=2^{1928}.2^2=\left(2^4\right)^{482}.4=16^{482}.4\)

=>16^482 có CSTC là 6=>16^482.4 có CSTC là 4=>2^1930 có CSTC là 4

=>9^1945-2^1930 có CSTC là 9-4=5 chia hết cho 5

Vậy ...

lmf câu b đc ko bn. mk viết sai đề. đề đúng là , 3vàx/5 = y/4 và x.y = 180

a)  \(0,75+\left(\dfrac{-1}{3}\right)-\dfrac{5}{18}=\dfrac{3}{4}+\left(\dfrac{-1}{3}\right)-\dfrac{5}{18}=\dfrac{5}{12}-\dfrac{5}{18}=\dfrac{5}{36}\)

c) \(\dfrac{4}{15}\cdot\dfrac{1}{3}\cdot\dfrac{15}{20}=\dfrac{4}{15}\cdot\dfrac{1}{3}\cdot\dfrac{3}{4}=\dfrac{5}{45}\cdot\dfrac{3}{4}=\dfrac{15}{180}=\dfrac{1}{12}\)

d) \(\left(\dfrac{-1}{9}\right)\cdot\left(\dfrac{15}{22}\right):\left(\dfrac{-25}{9}\right)=\dfrac{-5}{66}:\left(\dfrac{-25}{9}\right)=\dfrac{-5}{66}\cdot\left(\dfrac{9}{-25}\right)=\dfrac{-3}{-110}=\dfrac{3}{110}\)

a) \(0,75\) + \(\dfrac{-1}{3}\) - \(\dfrac{5}{18}\)= \(\dfrac{5}{12}\) - \(\dfrac{5}{18}\) = \(\dfrac{5}{36}\)

b) \(\dfrac{4}{15}\)x \(\dfrac{1}{3}\)x \(\dfrac{15}{20}\)= 4/45 x 15/20 = 1/15

c) -1/9 x 15/22 : -25/9 = -5/66 : -25/9 = 3/110

\(a.0,75+\left(\dfrac{-1}{3}\right)-\dfrac{5}{18}=\dfrac{75}{100}+\left(\dfrac{-6}{18}\right)-\dfrac{5}{18}=\dfrac{3}{4}-\dfrac{11}{18}=\dfrac{5}{36}\\ b.\dfrac{4}{15}.\dfrac{1}{3}.\dfrac{15}{20}=\dfrac{4}{15}.\dfrac{1}{3}.\dfrac{3}{4}=\dfrac{4.1.3}{15.3.4}=\dfrac{1.1.1}{15.1.1}=\dfrac{1}{15}\\ c.\dfrac{-1}{9}.\dfrac{15}{22}:\left(\dfrac{-25}{9}\right)=\dfrac{-1}{9}.\dfrac{15}{22}.\dfrac{-9}{25}=\dfrac{\left(-1\right).15.\left(-9\right)}{9.22.25}=\dfrac{\left(-1\right).3.\left(-1\right)}{1.22.5}=\dfrac{3}{110}\)

yhtyhyh

giúp mk vs. Mk k cho

\(x+\frac{2}{15}=\frac{1}{3}\)

\(x=\frac{1}{3}-\frac{2}{15}\)

\(x=\frac{1}{5}\)

h, \(h,\frac{1}{3}-\frac{2}{3}:x=\frac{1}{4}\)

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

\(\frac{2}{3}:x=\frac{1}{12}\)

\(x=\frac{2}{3}:\frac{1}{12}\)

\(x=8\)

ta có : `x/y=9/4=>x/9=y/4` và `x-y=15`

ADTC dãy tỉ số bằng nhau ta có :

`x/9=y/4 = (x-y)/(9-4)= 15/5=3`

`=> x/9=3=>x=3.9=27`

`=>y/4=3=>y=3.4=12`

vậy `x=27;y=12`