\(\left(3x+1\right)\left(x+3\right)=\left(2-x\right)\left(5-3x\right)\)

\(\Leftrightarrow3x^2+10x+3=10-11x+3x^2\)

\(\Leftrightarrow21x=7\)

\(\Leftrightarrow x=\frac{7}{21}=\frac{1}{3}\)

Vậy : \(x=\frac{1}{3}\)

4.(x+1)+3.x(x+2 )

= 4x + 4 + 3x²+6x

= 10x + 3 + 3x²

\(\left[\frac{2}{3x}-\frac{2}{x+1}\left(\frac{x+1}{3x}-x-1\right)\right]:\frac{x-1}{x}=\frac{2x}{x-1}\)( Điều kiện \(x\ne0\))

VT = \(\left[\frac{2}{3x}-\frac{2}{x+1}\left(\frac{x+1}{3x}-x-1\right)\right]:\frac{x-1}{x}\)

\(=\left[\frac{2}{3x}-\frac{2}{x+1}\left(\frac{x+1}{3x}-\frac{3x^2}{3x}-\frac{3x}{3x}\right)\right].\frac{x}{x-1}\)

\(=\left[\frac{2}{3x}-\frac{2}{x+1}\left(\frac{x+1-3x^2-3x}{3x}\right)\right].\frac{x}{x-1}\)

\(=\left(\frac{2}{3x}-\frac{2}{x+1}.\frac{-3x\left(x+1\right)+\left(x+1\right)}{3x}\right).\frac{x}{x-1}\)

\(=\left(\frac{2}{3x}-\frac{2}{x+1}.\frac{\left(x+1\right)\left(-3x+1\right)}{3x}\right).\frac{x}{x-1}\)

\(=\frac{2}{3x}-\frac{2x\left(-3x+1\right)}{3x}.\frac{x}{x-1}\)

\(=\left(\frac{2+6x-2}{3x}\right).\frac{x}{x-1}\)

\(=\frac{6x}{3x}.\frac{x}{x-1}\)

\(=\frac{2x}{x-1}=VP\)

Vậy đẳng thức được chứng minh . 

CÂU B  LÀM tt NHÉ

Xx4+(1/2+1/4+1/8+1/16)=23/16

Xx4=23/16-(1/2+1/4+1/8+1/16)

Xx4=1/2

X=1/2:4

X=1/8

1/8 nha bn

ako lop may mik lop 4 neu ban lop 4 thi ket ban nha

a) \(-7.\left|x-2013\right|+2012^0=\left|+1\right|\)

\(\Leftrightarrow-7.\left|x-2013\right|+1=1\)

\(\Leftrightarrow-7.\left|x-2013\right|=0\)

\(\Leftrightarrow\left|x-2013\right|=0\)

\(\Leftrightarrow x-2013=0\)

\(\Leftrightarrow x=2013\)

Vậy x = 2013

a) -7.|x-2013| + 2012⁰ = |+1|

-7.|x-2013| + 1 = 1

=> -7.|x-2013| = 0

=> | x-2013| = 0

=> x - 2013 = 0

x = 2013

\(-7.\left|x-2013\right|+1=\left|+1\right|\)

\(-7\left|x-2013\right|+1=1\)

\(-7\left|x-2013\right|=1-1\)

\(-7\left|x-2013\right|=0\)

\(\Rightarrow\left|x-2013\right|=0\)

\(\Rightarrow x-2013=0\)

\(x=2013\)

Vậy \(x=2013\)

\(\left(x-1\right)^2+\left|x^2-1\right|=0.\)

Vì \(\hept{\begin{cases}\left(x-1\right)^2\ge0\\\left|x^2-1\right|\ge0\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x-1=0\\x^2-1=0\end{cases}\Rightarrow x=1}\)

\(\left(1-\frac{1}{6}\right)\times\left(1-\frac{1}{7}\right)\times\left(1-\frac{1}{8}\right)\times\left(1-\frac{1}{9}\right)\times\left(1-\frac{1}{10}\right)\)

\(=\frac{5}{6}\times\frac{6}{7}\times\frac{7}{8}\times\frac{8}{9}\times\frac{9}{10}\)

\(=\frac{5\times6\times7\times8\times9}{6\times7\times8\times9\times10}\)

\(=\frac{5}{10}\)

\(=\frac{1}{2}\)

Đường Quỳnh Giang 50 giây trước (19:06)
Thống kê hỏi đáp
 Báo cáo sai phạm

(1−16 )×(1−17 )×(1−18 )×(1−19 )×(1−110 )

=56 ×67 ×78 ×89 ×910 

=5×6×7×8×96×7×8×9×10 

=510 

(1-1/6)×(1-1/7)×(1-1/8)×(1-1/9)×(1-1/10)

=(6/6-1/6)×(7/7-1/7)×(8/8-1/8)×(9/9-1/9)×(10/10-1/10)

=5/6×6/7×7/8×8/9×9/10

=5/10 

(Bạn gạch đi những số giống nhau nha)

Ví dụ:5/6×6/7=5/7(gạch bỏ số 6)