a/ 64884

b/ 3050

21628 x 3 = 64884                       15250: 5 = 3050 45603 + 12908 = 32695 67013- 23114 = 43899

a) \(\Rightarrow x^2+4x+25-x^2=3\Rightarrow4x=-22\Rightarrow x=-\dfrac{11}{2}\)

b) \(\Rightarrow\left(4x+3-2x+3\right)\left(4x+3+2x-3\right)=0\)

\(\Rightarrow2\left(x+3\right).6x=0\)

\(\Rightarrow\left[{}\begin{matrix}x=0\\x=-3\end{matrix}\right.\)

a) x(x-3)+(x-3)=0

<=>(x-3)(x+1)=0

<=>x-3=0 hoặc x+1=0

<=>x=3 hoặc x=-1

b) 7x(x-5)-x+5=0

<=>(7x-1)(x-5)=0

<=>7x-1=0 hoặc x-5=0

<=>x=1/7 hoặc x=5

a: Ta có: \(x\left(x-3\right)+\left(x-3\right)=0\)

\(\Leftrightarrow\left(x-3\right)\left(x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)

b: Ta có: \(7x\left(x-5\right)-x+5=0\)

\(\Leftrightarrow\left(x-5\right)\left(7x-1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=5\\x=\dfrac{1}{7}\end{matrix}\right.\)

Lời giải:

a.

$\frac{2}{3}+\frac{1}{3}:3\times x=20\text{%}$
$\frac{2}{3}+\frac{1}{9}\times x=\frac{1}{5}$

$\frac{1}{9}\times x=\frac{1}{5}-\frac{2}{3}=\frac{-7}{15}$

$x=\frac{-7}{15}: \frac{1}{9}=\frac{-21}{5}$
b.

$\frac{3-x}{5-x}=\frac{6}{11}$
$\Rightarrow 6(5-x)=11(3-x)$

$\Rightarrow 30-6x=33-11x$

$\Rightarrow 5x=3$

$\Rightarrow x=\frac{3}{5}$

a: x=9/2-3/7=57/14

b: =>x=7/5x5/7=1

c: =>x=11/3:3/8=11/3x8/3=88/9

a : x = \(\dfrac{9}{2}\) - \(\dfrac{3}{7}\) = \(\dfrac{57}{14}\)

b : = > x = \(\dfrac{7}{5}\) x\(\dfrac{5}{7}\) = 1

 c : = >  \(\dfrac{11}{3}\) : \(\dfrac{3}{8}\) = \(\dfrac{11}{3}\) x \(\dfrac{8}{3}\) = \(\dfrac{88}{9}\)

\(a,x=\dfrac{1}{2}-\dfrac{2}{5}\)

\(x=\dfrac{1}{10}\)

\(b,x+\dfrac{3}{7}=\dfrac{7}{10}\)

\(x=\dfrac{7}{10}-\dfrac{3}{7}\)

\(x=\dfrac{19}{70}\)

\(c,19-x=\dfrac{17}{20}\)

\(x=19-\dfrac{17}{20}\)

\(x=\dfrac{363}{20}\)

a,1/10

b,19/70

c,18/4

x=36320

a: =>x^2-25-x^2-3x=10

=>-3x=35

=>x=-35/3

b: =>4x^2-9-4(x^2+4x+4)=5

=>4x^2-9-4x^2-16x-16-5=0

=>-16x-30=0

=>x=-15/8

c: =>9x^2+45x-9x^2+4=7

=>45x=3

=>x=1/15

d: =>x^3+3x^2+3x+1-x^3-3x^2+5x=8

=>8x=7

=>x=7/8