456 nha

= 456.

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Ai tk cho mình mình tk lại.

=57x2+57x3+57x1+57x1+57x1

=57x(2+3+1+1+1)

=57x8

=456

a) A=58

a) Ta có: \(7-\left(2x+4\right)=-\left(x+4\right)\)

\(\Leftrightarrow7-2x-4=-x-4\)

\(\Leftrightarrow-2x+3+x+4=0\)

\(\Leftrightarrow-x+7=0\)

\(\Leftrightarrow-x=-7\)

hay x=7

Vậy: S={7}

b) Ta có: \(\dfrac{2+x}{5}-0.5x=\dfrac{1-2x}{4}+0.25\)

\(\Leftrightarrow\dfrac{4\left(2+x\right)}{20}-\dfrac{0.5x\cdot20}{20}=\dfrac{5\left(1-2x\right)}{20}+\dfrac{20\cdot0.25}{20}\)

\(\Leftrightarrow4\left(2+x\right)-10x=5\left(1-2x\right)+5\)

\(\Leftrightarrow8+4x-10x=5-10x+5\)

\(\Leftrightarrow-6x+8=-10x+10\)

\(\Leftrightarrow-6x+8+10x-10=0\)

\(\Leftrightarrow4x-2=0\)

\(\Leftrightarrow4x=2\)

hay \(x=\dfrac{1}{2}\)

Vậy: \(S=\left\{\dfrac{1}{2}\right\}\)

d) Ta có: \(\dfrac{x-1}{59}+\dfrac{x-2}{58}+\dfrac{x-3}{57}=\dfrac{x-59}{1}+\dfrac{x-58}{2}+\dfrac{x-57}{3}\)

\(\Leftrightarrow\dfrac{x-1}{59}-1+\dfrac{x-2}{58}-1+\dfrac{x-3}{57}-1=\dfrac{x-59}{1}-1+\dfrac{x-58}{2}-1+\dfrac{x-57}{3}-1\)

\(\Leftrightarrow\dfrac{x-60}{59}+\dfrac{x-60}{58}+\dfrac{x-60}{57}=\dfrac{x-60}{1}+\dfrac{x-60}{2}+\dfrac{x-60}{3}\)

\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}\right)-\left(x-60\right)\left(1+\dfrac{1}{2}+\dfrac{1}{3}\right)=0\)

\(\Leftrightarrow\left(x-60\right)\left(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\right)=0\)

mà \(\dfrac{1}{59}+\dfrac{1}{58}+\dfrac{1}{57}-1-\dfrac{1}{2}-\dfrac{1}{3}\ne0\)

nên x-60=0

hay x=60

Vậy: S={60}

1) 5^2 . x + 2^4 . x = 123 

=> 25 .x + 16 .x = 123

 =>  x ( 25 + 16 ) = 123 

=> x . 41               = 123 

=> x                     = 123 : 41 

=> x                       = 3 

b, 3^6 : 3 ^ 3 + 5.x = 57

  => 3^3 + 5.x = 57 

=> 27         + 5x  = 57 

=> 5x                   = 57 - 27

=> 5x                     = 30

=>  x                      = 30 : 5 

=> x                        = 6 

Bạn tính theo cách a.b + a.c = a(b+c)

Em 2k9 , e chỉ đc học sơ qua thôi nha

5 x (X-3) + 3² = 5² x 2 - 6

=>5x(x-3)+9= 25x 2-6

=>5x(x-3)+9=44

=> 5x(x-3) = 35

=>x-3= 7

=>x =10

a)5 x (X-3)+3²=5² x 3-6

5 x (X-3)+9=25 x 3-6

5 x (X-3)+9=75-6

5 x (X-3)+9=69

5 x (X-3)=69-9=60

X-3=60:5=12

X=12+3=15

b)57 x 35 +23 x 57 + 58 x 43

=57 x 35 +23 x 57 +(57+1) x 43

=57 x 35 +23 x 57 +57 x 43 + 43

=57 x (35+23+43)+43

=57 x 101 + 43

=57 x (100+1)+43

=57 x 100 +57 +43

=5700 + 100=5800

\(5\times\left(x-3\right)+3^2=5^2\times2-6\)

\(5\times\left(x-3\right)+9=25\times2-6\)\(\)

\(5\times\left(x-3\right)=50-6-9\)

\(5\times\left(x-3\right)=35\)

\(x-3=35:5\)

\(x-3=7\)

\(x=7+3\)

\(x=10\)

D

a) \(\frac{2}{5}-\frac{2}{5}x+\frac{1}{3}=x-\frac{7}{15}\)

\(\Leftrightarrow\frac{11}{15}-\frac{2x}{5}=x-\frac{7}{15}\)

\(\Leftrightarrow\frac{2x}{5}=x-\frac{7}{15}-\frac{11}{15}\)

\(\Leftrightarrow-\frac{2x}{5}=x-\frac{5}{6}\)

\(\Leftrightarrow-\frac{2x}{5}=x.5-\frac{5}{6}.5\)

\(\Leftrightarrow-2x=5x-6\)

\(\Leftrightarrow-2x=-5x-6-5x\)

\(\Leftrightarrow-7x=-6\)

\(\Rightarrow x=\frac{6}{7}\)

\(\left(\dfrac{x+1}{55}+\dfrac{x+2}{56}+\dfrac{x+3}{57}+\dfrac{x+4}{58}\right)-4=0\)

<=>\(\dfrac{x+1}{55}+\dfrac{x+2}{56}+\dfrac{x+3}{57}+\dfrac{x+4}{58}=4\)

<=>\(\dfrac{x+1}{55}-1+\dfrac{x+2}{56}-1+\dfrac{x+3}{57}+\dfrac{x+4}{58}-1=4-4\)

<=>\(\dfrac{x+1}{55}-\dfrac{55}{55}+\dfrac{x+2}{56}-\dfrac{56}{56}+\dfrac{x+3}{57}-\dfrac{57}{57}+\dfrac{x+4}{58}-\dfrac{58}{58}=0\)

<=>\(\dfrac{x-54}{55}+\dfrac{x-54}{56}+\dfrac{x-54}{57}+\dfrac{x-54}{58}=0\)

<=>\(\left(x-54\right)\left(\dfrac{1}{55}+\dfrac{1}{56}+\dfrac{1}{57}+\dfrac{1}{58}\right)=0\)

<=>x-54=0

<=>x=54

vậy phương trình có tập nghiệm là S={54}

=>\(\left(\dfrac{x+1}{55}-1\right)+\left(\dfrac{x+2}{56}-1\right)+\left(\dfrac{x+3}{57}-1\right)+\left(\dfrac{x+4}{58}-1\right)=0\)

=>x-54=0

=>x=54