Ta có sơ đồ:

Lúc đầu: Khi bán: 2 quả Còn lại: 28 quả Lúc đầu có số quả cam là: (28+2):5x9=54(quả)

- Số trứng đó là : 

28 : 4 phần 9 + 2 = 65 [ quả ]

b1:

\(-5.\left(x-\frac{1}{5}\right)-\frac{1}{2}\left(x-\frac{2}{3}\right)=\frac{3}{2}x-\frac{5}{6}\Leftrightarrow-5x+1-\frac{1}{2}x+\frac{1}{3}=\frac{3}{2}x-\frac{5}{6}\)

\(\Leftrightarrow-\frac{11}{2}x+\frac{4}{3}=\frac{3}{2}x-\frac{5}{6}\Leftrightarrow-\frac{11}{2}x-\frac{3}{2}x=-\frac{5}{6}-\frac{4}{3}\Leftrightarrow-7x=-\frac{13}{6}\)

\(\Leftrightarrow x=\frac{-13}{6}:\left(-7\right)=\frac{13}{42}\)

b2:

a)\(3^{3x-1}=9^{x-2}\Leftrightarrow3^{3x-1}=\left(3^2\right)^{x-2}\Leftrightarrow3^{3x-1}=3^{2x-4}\Leftrightarrow3x-1=2x-4\)

<=>3x-2x=-4+1<=>x=-3

b)\(\left(x-1\right)^4=\left(x-1\right)^6\Leftrightarrow\left(x-1\right)^4-\left(x-1\right)^6=0\Leftrightarrow\left(x-1\right)^4\left[1-\left(x-1\right)^2\right]=0\)

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

\(\Leftrightarrow\left(x-1\right)^4\left(-x^2+2x\right)=0\Leftrightarrow\left(x-1\right)^4.\left(-x\right).\left(x-2\right)=0\)

<=>(x-1)⁴=0 hoặc -x=0 hoặc x-2=0 <=> x=1 hoặc x=0 hoặc x=2

2/3 x ( 3/1.4 + 3/4.7 + 3/7.10 + ... + 3/70.73 - 2x = 1

2/3 x ( 1 - 1/4 + 1/4 - 1/7 + ... + 1/70 - 1/73 ) - 2x = 1

2/3 x ( 1- 1/73 ) - 2x = 1

2/3 x 72/73 - 2x = 1

48/73 - 2x = 1

2x = 48/73 - 1

2x = -25/73

x = -25/73 : 2 

x = -25/146 

Vậy x = -25/146

Tk nha !!

Dư 8 nhá!!!

uk thanks ông nha

\(\frac{b}{a}\).(\(\frac{1}{n}\) - \(\frac{1}{n+a}\))

= \(\frac{b}{a}\).\(\frac{n+a-n}{n\left(n+a\right)}\)

= \(\frac{b}{a}.\) \(\frac{\left(n-n\right)+a}{n\left(n+a\right)}\)

= \(\frac{b}{a}\).\(\frac{a}{n\left(n+a\right)}\)

= \(\frac{b}{n\left(n+a\right)}\) (đpcm)

Ta có:\(\frac{1}{6}+\frac{1}{66}+\frac{1}{176}+...+\frac{1}{\left(5n+1\right)\left(5n+6\right)}\)

        \(=\frac{1}{5}.\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+...+\frac{5}{\left(5n+1\right)\left(5n+6\right)}\right)\)

        \(=\frac{1}{5}.\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+...+\frac{1}{5n+1}-\frac{1}{5n+6}\right)\)

        \(=\frac{1}{5}.\left(1-\frac{1}{5n+6}\right)\)

        \(=\frac{1}{5}.\left(\frac{5n+5}{5n+6}\right)=\frac{n+1}{5n+6}\left(\text{đ}pcm\right)\)

bo thua lam duoc

các bạn giải hộ mình được không càn lắm

1) 4n - 3 chia hết cho 2n + 1

4n + 2 - 5 chia hết cho 2n + 1

5 chia hết cho 2n + 1

2n + 1 thuộc U(5) = {-5;-1;1;5}

n thuộc {-3 ; -1 ; 0 ; 2}

Nguyễn Ngọc Quý trở lại òi à