a, \(\left(x-\frac{1}{2}\right)^3=\frac{1}{27}\)\(\Rightarrow\left(x-\frac{1}{2}\right)^3=\left(\frac{1}{3}\right)^3\)\(\Rightarrow x-\frac{1}{2}=\frac{1}{3}\)\(\Rightarrow x=\frac{5}{6}\)

b, \(\left(x-1\right)^{x+2}=\left(x-1\right)^{x+6}\)

\(\Rightarrow\left(x-1\right)^{x+2}-\left(x-1\right)^{x+6}=0\)

\(\Rightarrow\left(x-1\right)^{x+2}\left[1-\left(x-1\right)^4\right]=0\)

\(\Rightarrow\orbr{\begin{cases}\left(x-1\right)^{x+2}=0\\1-\left(x-1\right)^4=0\end{cases}}\Rightarrow\orbr{\begin{cases}x-1=0\\\left(x-1\right)^4=1\end{cases}}\Rightarrow\orbr{\begin{cases}x=1\\\left(x-1\right)^4=1\end{cases}}\)

Giải: \(\left(x-1\right)^4=1\)\(\Rightarrow\orbr{\begin{cases}x-1=1\\x-1=-1\end{cases}}\Rightarrow\orbr{\begin{cases}x=2\\x=0\end{cases}}\)

c, Vì \(\left(x+20\right)^{100}\ge0\)\(\forall x\inℝ\); \(\left|y+4\right|\ge0\)\(\forall y\inℝ\)

\(\Rightarrow\left(x+20\right)^{100}+\left|y+4\right|\ge0\)\(\forall x,y\inℝ\)

Dấu " = " xảy ra <=> \(\hept{\begin{cases}x+20=0\\y+4=0\end{cases}}\Rightarrow\hept{\begin{cases}x=-20\\y=-4\end{cases}}\)

d, \(2^{x-1}=16\)\(\Rightarrow2^{x-1}=2^4\)=> x - 1 = 4 => x = 5 

\x . 3,9 + x . 0,1 = 2,7

x . (3,9 + 0,1) = 2,7

x . 4 = 2,7

x = 2,7 : 4

x = 0,675

b) 12,3 : x - 4,5 : x = 15

(12,3 - 4,5) : x = 15

7,8 : x = 15

x = 7,8 : 15

x = 0,52

Cảm ơn bạn nhìu

a) \(5x-18=72\)

\(5x=72+18\)

\(5x=100\)

\(x=100\div5\)

\(x=20\)

b) \(\left(x-36\right)-32=0\)

\(x-36=32\)

\(x=32+36\)

\(x=68\)

c) \(156-\left(x+6\right)=82\)

\(x+6=156-82\)

\(x-6=74\)

\(x=74+6\)

\(x=80\)

d) \(2^x=16\)

\(2^x=2^4\)

=> x = 4

ai giúp mình với,bài khó quá.

5m2 3dm2 25cm2 = 10325 cm2

404dm2 = 4m2 400cm2

10400cm2 = 1m2 4dm2

12m2 500cm2 = 1205m2

k cho mình nha !!!

a, 50325 m2

b,400m2 0,04cm2

c,1m2 4dm2

d,1205m2

475 x 87 - 87 x 373 - 87 - 87

= 475 x 87 - 87 x 373 - 87 x 1 - 87 x 1

= 87 x (475 - 373 - 1 - 1)

= 87 x 100

= 8700

234 x 96 + 2 x 234 + 234 + 234

= 234 x 96 + 2 x 234 + 234 x 1 + 234 x 1

= 234 x (96 + 2 + 1 + 1)

= 234 x 100

= 23400

\(\frac{1238978}{5476}=226,2560263\)

#Học tốt!!!

~NTTH~

thanks

1) 12,3 : 10 = 12,3 x 0,1

12,3 : 100 = 12,3 x 0,01

12,3 : 1000 = 12,3 x 0,001

2) Số xi  măng đã dùng là:

   23,45 x 1/10 = 2,345 (tấn)

Số xi măng còn lại là:

   23,45 - 2,345 = 21,105 (tấn)

      Đ/S:..........

63l nha bn

79 lít

#Học tốt!!!^{(sai thì thôi)}

~NTTH~