`12=3.2^2`

`15=3.5`

`=>MC` là: `2^2 .3.5=60`

60

0,25

\(\dfrac{1}{4}\)= 0.25

1. What will you do?
I will organize free tutoring classes, donate books and school supplies, and raise funds for students in need.

2. Why do you choose to do them?
Because education is very important, and I want to help students have better opportunities to learn and succeed.

3. Do you think the students in need will receive benefits? Why?
Yes, they will. They can improve their knowledge, have enough materials to study, and feel more confident about their future.

4. How can you make more people know about your voluntary activities?
I can share information on social media, invite friends to join, and cooperate with schools or local organizations to spread the message.

B=(1/4.9+1/9.14+...+1/44.49).1-3-5-...-49/89

B=1/5(1/4-1/9+1/9-1/14+...+1/44-1/49).1-(3+5+...+49)/89

B=1/5(1/4-1/49).1-24.52:2/89

B=9/196.-7

B=-9/28

Ta có \(\frac{1-3-5-..-49}{89}=\frac{1-\left(3+5+7+...+49\right)}{89}\)

\(=\frac{1-\left[\left(49-3\right):2+1\right].\left(\frac{49+3}{2}\right)}{89}=\frac{1-624}{89}=-7\)

Lại có \(\frac{1}{4.9}+\frac{1}{9.14}+....+\frac{1}{44.49}=\frac{1}{5}\left(\frac{5}{4.9}+\frac{5}{9.14}+...+\frac{5}{44.49}\right)\)

\(=\frac{1}{5}\left(\frac{1}{4}-\frac{1}{9}+\frac{1}{9}-\frac{1}{14}+...+\frac{1}{44}-\frac{1}{49}\right)=\frac{1}{5}\left(\frac{1}{4}-\frac{1}{49}\right)=\frac{1}{5}.\frac{45}{196}=\frac{9}{196}\)

Khi đó \(B=\frac{9}{196}.\left(-7\right)=-\frac{9}{28}\)

có em nè

mk nè

1 + 1 = 2

hok tok

1+1=2

miễn phí thêm

2+2=4

4+4=8

8+8=16

k nha. thanks bn mk đang kiếm điểm

giúp đất tơi hơi ok con d d

Giun đất có tác dụng đào bới làm xốp đất.Phân giun đất là thứ phân bón sạch,rất tốt cho thực vật. Giun còn là phương tiện xử lí rác làm sạch môi trường.Giun đất có thể ăn vì nó có 70 phần trăm là đạm. Giun đất có thể làm thuốc chữa bệnh.

\(\left(x+2\right)\left(\dfrac{360}{x}-6\right)=360\)

\(ĐK:x\ne0\)

\(\Leftrightarrow\left(x+2\right)\left(\dfrac{360-6x}{x}\right)=360\)

\(\Leftrightarrow360-6x+\dfrac{720-12x}{x}=360\)

\(\Leftrightarrow360x-6x^2+720-12x=360x\)

\(\Leftrightarrow6x^2+12x-720=0\)

\(\Delta=12^2-4.6.\left(-720\right)\)

    \(=17424>0\)

`->` pt có 2 nghiệm

\(\left\{{}\begin{matrix}x_1=\dfrac{-12-\sqrt{17424}}{12}=-12\\x_2=\dfrac{-12+\sqrt{17424}}{12}=10\end{matrix}\right.\) ( tm )

Vậy \(S=\left\{-12;10\right\}\)

`48/[x+4]+48/[x-4]=5`           `ĐK: x \ne +-4`

`<=>[48(x-4)+48(x+4)]/[(x-4)(x+4)]=[5(x+4)(x-4)]/[(x-4)(x+4)]`

   `=>48x-192+48x+192=5x^2-80`

`<=>5x^2-96x-80=0`

`<=>5x^2-100+4x-80=0`

`<=>5x(x-20)+4(x-20)=0`

`<=>(x-20)(5x+4)=0`

`<=>` $\left[\begin{matrix} x=20\\ x=\dfrac{-4}{5}\end{matrix}\right.$   (t/m)

Vậy `S={-4/5;20}`

ĐK : \(x\ne\pm4\)

\(\Leftrightarrow\cdot\dfrac{48\left(x+4\right)+48\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}=\dfrac{5\left(x+4\right)\left(x-4\right)}{\left(x+4\right)\left(x-4\right)}\)

\(\Leftrightarrow48x+192+48x-192==5x^2-80\)

\(\Leftrightarrow96x=5x^2-80\)

\(\Leftrightarrow5x^2-96x-80=0\)

\(\Leftrightarrow5x^2+4x-100-80=0\)

\(\Leftrightarrow4\left(x-20\right)+5x\left(x-20\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x-20=0\\5x=-4\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=20\\x=-\dfrac{4}{5}\end{matrix}\right.\)

Quà sinh nhật năm ngoái bạn có là gì?

Cái này bạn phải tự trả lời thôi, mình dịch ra giùm rồi đó +=*

x2r3x