nhanh len mk can gap lam

\(5\frac{9}{10}:\frac{3}{2}-\left(2\frac{1}{3}x4\frac{1}{2}-2\frac{1}{2}\right):\frac{7}{4}\)

=\(\frac{59}{10}:\frac{3}{2}-\left(\frac{7}{3}x\frac{9}{2}-\frac{5}{2}\right):\frac{7}{4}\)

=\(\frac{118}{30}-\left(\frac{63}{6}-\frac{5}{2}\right)x\frac{4}{7}\)

=\(\frac{118}{30}-\left(\frac{63}{6}-\frac{15}{6}\right)x\frac{4}{7}\)

=\(\frac{118}{30}-8x\frac{4}{7}\)

=\(\frac{118}{30}-\frac{32}{7}\)

sau bn tự tính nha

Chữ số hàng trăm là:

20 : 4 = 5

Coi chữ số hàng chục là 3 phần thì chữ số hàng đơn vị là 2 phần

Chữ số hàng chục là:

( 20 - 5 ) : ( 3 + 2 ) x 3 = 9

Chữ số hàng đơn vị là:

20 - 9 - 5 = 6

Vậy số cần tìm là 596

596 đó

= 270 nha bạn

1+1+2+2+3+3+4+4+5+5+6+6+7+7+8+8+9+9=2+4+6+8+10+12+14+16+18

                                                                        =(2+8)+(4+6)+10+(12+18)+(14+16)

                                                                        =10+10+10+30+30

                                                                        =30+30+30

                                                                        =30x3

                                                                        =90

= 270 nha

\(a,\left(2y+1\right)^3=125\)

\(\Leftrightarrow2y+1=\sqrt[3]{125}=5\)

\(\Leftrightarrow2y=5-1=4\)

\(\Rightarrow y=2\)

\(b,\left(y-5\right)^4=\left(y-5\right)^6\)

\(\Leftrightarrow\left(y-5\right)^4-\left(y-5\right)^6=0\)

\(\Leftrightarrow\left(y-5\right)^4\left[1-\left(y-5\right)^2\right]=0\)

\(\Leftrightarrow\left(y-5\right)^4\left(1-y+5\right)\left(1+y-5\right)=0\)

\(\Leftrightarrow\left(y-5\right)^4\left(6-y\right)\left(y-4\right)=0\)

Vì \(\left(y-5\right)^4>0\forall y\)

\(\Rightarrow\left[{}\begin{matrix}6-y=0\\y-4=0\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}y=6\\y=4\end{matrix}\right.\)

a) \(\left(2y+1\right)^3=125\)

\(\Leftrightarrow\left\{{}\begin{matrix}\left(2y+1\right)^3=5^3\\\left(2y+1\right)^3=\left(-5\right)^3\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}2y+1=5\\2y+1=-5\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}2y=4\\2y=-6\end{matrix}\right.\)

\(\Leftrightarrow\left\{{}\begin{matrix}y=2\\y=-3\end{matrix}\right.\)

Vậy ...................

b1

a) \(\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}+\dfrac{1}{8.9}+\dfrac{1}{9.10}\)

\(=\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}\)

\(=\dfrac{1}{5}-\dfrac{1}{10}\)

\(=\dfrac{2}{10}-\dfrac{1}{10}\)

\(=\dfrac{1}{10}\)

b) \(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{99.100}\)

\(=\dfrac{1}{1}-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{99}-\dfrac{1}{100}\)

\(=\dfrac{1}{1}-\dfrac{1}{100}\)

\(=\dfrac{99}{100}\)

c) \(\dfrac{2}{3.5}+\dfrac{2}{5.7}+\dfrac{2}{7.9}+\dfrac{2}{9.11}\)

\(=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}\)

\(=\dfrac{1}{3}-\dfrac{1}{11}\)

\(=\dfrac{8}{33}\)

d) \(\dfrac{2}{3.5}+\dfrac{2}{5.7}+...+\dfrac{2}{99.101}\)

\(=\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+...+\dfrac{1}{99}-\dfrac{1}{101}\)

\(=\dfrac{1}{3}-\dfrac{1}{101}\)

\(=\dfrac{98}{303}\)

A= 3( 1+3+3^2+3^3+3^4+3^5+3^6+3^7+3^8) chia hết cho 3

mk ko hieu ban co the giai thich ra duoc ko

mik nhân từng số mà sai thì đừng có k nha hihihi thật ra bằng kết quả này hihihi

1*2*3*4/8 *9*10*7=15.120 

ko bít đâu nha hihi

\(\frac{2x3x2x2}{2x2x2x3x3x2x5x7}\)=\(\frac{1}{2x3x5x7}\)=\(\frac{1}{210}\)

khanh ly oi tinh nhanh ma cach ban la tinh cham

de bai 1*2*3*4/8*9*10*7

cach minh la 8/4;10/2;9/3;7/1 nhung 1 dung truoc nen tanh 1/7 va=1/7

8/4=2;10/2=5;9/3=3 nen ket qua la phan so va =30/7