ta có : Khi chia cho 5 xảy ra 5 số dư là 0 , 1 ,2 ,3 , 4. vậy số dư lớn nhất có thể có là 4 . số bao nhiêu chữ số cũng thế cả bạn ạ !!!

1.a) \(\left(2x+1\right)^2-49x^2+56x-16\)

\(=\left(2x+1\right)^2-\left[\left(7x\right)^2-2.8.7x-4^2\right]\)

\(=\left(2x+1\right)^2-\left(7x-4\right)^2\)

\(=\left(2x+1+7x-4\right)\left(2x+1-7x+4\right)\)

\(=\left(9x-3\right)\left(5-5x\right)\)

Ta có : \(\dfrac{2x-3}{4}=\dfrac{-36}{3-2x}\)

\(\Leftrightarrow\dfrac{2x-3}{4}=\dfrac{36}{-\left(3-3x\right)}\)

\(\Leftrightarrow\dfrac{2x-3}{4}=\dfrac{36}{2x-3}\)

\(\Leftrightarrow\left(2x-3\right)\left(2x-3\right)=4.36=144\)

\(\Leftrightarrow\left(2x-3\right)^2=\left(\pm12\right)^2\)

\(\Leftrightarrow\left[{}\begin{matrix}2x-3=12\\2x-3=-12\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=7,5\\x=-4,5\end{matrix}\right.\)

Vậy \(x=7,5\) hoặc \(x=-4,5\)

Tik mik nha!!!

Ta có : \(\dfrac{x+3}{2}=\dfrac{x-3}{5}\)

\(\Leftrightarrow5\left(x+3\right)=2\left(x-3\right)\)

\(\Leftrightarrow5x+15=2x-6\)

\(\Leftrightarrow3x=-21\Leftrightarrow x=-7\)

Vậy x = -7.

bài này còn 1 cách giải nữa nhé bạn !!!

tik mik nha !!!

tick mik đi mik tick bạn rùi nè, mik trả lowpf đúng mè

\(A=3+6+9+12+...+2007\)

\(A=\dfrac{\left(2007+3\right)\left(\dfrac{2007-3}{3}+1\right)}{2}\)

\(A=\dfrac{2010.669}{2}=672235\)

\(B=\dfrac{\dfrac{2006}{2}+\dfrac{2006}{3}+\dfrac{2006}{4}+...+\dfrac{2006}{2007}}{\dfrac{2006}{1}+\dfrac{2005}{2}+\dfrac{2004}{3}+...+\dfrac{1}{2006}}\)

\(B=\dfrac{2006\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2007}\right)}{2006+\left(\dfrac{2005}{2}+1\right)+\left(\dfrac{2004}{3}+1\right)+...\left(\dfrac{1}{2006}+1\right)-2005}\)

\(B=\dfrac{2006\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2007}\right)}{\dfrac{2007}{2007}+\dfrac{2007}{2}+\dfrac{2005}{3}+...+\dfrac{2007}{2006}}\)

\(B=\dfrac{2006\left(\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2007}\right)}{2007\left(\dfrac{1}{2007}+\dfrac{1}{2}+\dfrac{1}{3}+...+\dfrac{1}{2016}\right)}=\dfrac{2006}{2007}\)

tik mik nha !!!

1. The painting is more expensive than my painting ( not as ... as ).

2. The painting is bigger than the photo graph ( not as ... as ).

3. This picture is the same as the picture in our room ( not different from ).

4. This film is more interesting than the one we saw last week ( not as ... as ) .

5. The joyrney was shorter than we thought at first ( not as ... as ) .

\(\Rightarrow\) The journey was not as long as we thought at first.

tik mik nha !!!

Mik chỉ làm 1 bài sau đó bạn tự làm nhé !!!

a) ta có : \(10^{15}+8=1000...000+8=1000...008\)

(ở giữa dấu chấm là rất nhiều số 0)

Ta có : 1000...008 tận cùng là 8

\(\Rightarrow100...008⋮2\)(1)

Tổng các chữ số của 100...008: \(1+0+0+...+0+8=9⋮9\)

\(\Rightarrow1000...08⋮3\)(2)

Từ (1) VÀ (2)=> \(10^{15}+8⋮2\) VÀ 9

TIK MIK NHA !!!

1.we enjoy ( sit ) sitting in the garden

2. I would like (buy) to buy a new car

3. do you hate ( wash) washing ?

4.she can (play) play the piano

5. you should avoid ( swoke) smoking.

tik mik nha !!!

chứng minh b nằm giữa a và d

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cứ làm vậy sẽ ra