a,

đoạn 9x-6-> 2x-6=0

=> x=3

b,6x^2+13x+5=6x^2-20x+6

33x=1

=>x=1/33

a) (x+1)(x+9)=(x+3)(x+5) 

<=>x^2+10x+9=x^2+8x+15

<=>x^2+10x+9-x^2-8x-15=0

<=>9x-6=0 phải là 2x - 6

<=>9x=6

<=>x=6/9=2/3 => S= 2/3

d) (3x+5)(2x+1)=(6x-2)(x-3)

<=>6x^2+13x+5=6x^2-16x+6 phải là 6x^2 - 20x + 6

<=>6x^2+13x+5-6x^2+16x-6=0

<=>29x-1=0

<=>29x=1

<=>x=1/29

1313/1616 + 3/5 = 131313/161616 + 9/15

"=" nha em

a) \(x+x\times\frac{1}{4}\div\frac{2}{7}+x\div\frac{2}{9}=255\)

\(\Rightarrow x+x\times\frac{1}{4}\times\frac{7}{2}+x\times\frac{9}{2}=255\)

\(\Rightarrow x+x\times\frac{7}{8}+x\times\frac{9}{2}=255\)

\(\Rightarrow x\times\left(1+\frac{7}{8}+\frac{9}{2}\right)=255\)

\(\Rightarrow x\times\frac{51}{8}=255\)

\(\Rightarrow x=255\div\frac{51}{8}\)

\(\Rightarrow x=40\)

Vậy x = 40

b) \(1\frac{1}{21}\div\left(15,75-15\frac{1}{5}\right)+2\frac{1}{12}\div\left(7\frac{3}{4}-7,25\right)\)

\(=\frac{22}{21}\div\left(15,75-\frac{76}{5}\right)+\frac{25}{12}\div\left(\frac{31}{4}-7,25\right)\)

\(=\frac{22}{21}\div\frac{11}{20}+\frac{25}{12}\div\frac{1}{2}\)

\(=\frac{40}{21}+\frac{25}{6}\)

\(=\frac{85}{14}\)

_Chúc bạn học tốt_

X + X x 1/4 : 2/7 + x : 2/9 = 225

X + X x 1/4 x 7/2 + X x 9/2 = 225

X + X x 7/8 + X x 9/2 = 225

X x ( 1 + 7/8 + 9/2 ) = 225

X x 51/8 = 225

X = 225 : 51/8

X = 600/17

Dấu * là dấu nhân nhà m.ng ai giúp mik mik k k chừa 1 ai :3

\(\frac{5}{6}+\frac{3}{4}< \frac{19}{11}\)

\(\frac{17}{12}-\frac{9}{8}< \frac{1}{3}\)

\(\frac{4}{9}\times\frac{6}{5}=\frac{8}{15}\)

\(\frac{15}{4}:\frac{3}{8}>8\)

z đâu ????

cái đề nó cho z thui bn ak.