1) \(=\left(9x^2-25y^2\right)-\left(6x-10y\right)=\left(3x-5y\right)\left(3x+5y\right)-2\left(3x-5y\right)=\left(3x-5y\right)\left(3x+5y-2\right)\)

2) \(=9x^2y^2-\left(x^2-2xy+y^2\right)=9x^2y^2-\left(x-y\right)^2=\left(3xy-x+y\right)\left(3xy+x-y\right)\)

TL:

Ta có:

10 có mũ bao nhiêu đi nữa, thì + 10⁹ hay 10⁸ +..v.v

Thì số cuối của dãy số vẫn băng 0 nên

=> 10⁹+10⁸+10⁷ chia hết cho 2

Học Tốt👍

\(=A\cdot\left(40+60+80-180\right)+2023\)

=0+2023

=2023

d: Ta có: ƯCLN(a,b)=2

=>\(\left\{{}\begin{matrix}a=2x\\b=2y\end{matrix}\right.\)

\(a\cdot b=120\)

=>\(2x\cdot2y=120\)

=>\(x\cdot y=30\)

mà x,y là các số nguyên dương

nên \(\left(x,y\right)\in\left\{\left(1;30\right);\left(2;15\right);\left(3;10\right);\left(5;6\right);\left(6;5\right);\left(10;3\right);\left(15;2\right);\left(30;1\right)\right\}\)

=>\(\left(a,b\right)\in\left\{\left(2;60\right);\left(4;30\right);\left(6;20\right);\left(10;12\right);\left(12;10\right);\left(20;6\right);\left(30;4\right);\left(60;2\right)\right\}\)

Bài 2:

a) \(\dfrac{2}{15}-\dfrac{7}{10}=\dfrac{4}{30}-\dfrac{21}{30}=-\dfrac{17}{30}\)

b) \(\dfrac{-3}{14}+\dfrac{2}{21}=\dfrac{-9}{42}+\dfrac{4}{42}=\dfrac{-5}{42}\)

c) \(\dfrac{-6}{9}+\dfrac{-12}{16}=\dfrac{-96}{144}+\dfrac{-108}{144}=\dfrac{-204}{144}=-\dfrac{17}{12}\)

Bài 3: 

a) \(\dfrac{3}{8}+\dfrac{-5}{6}=\dfrac{3}{8}-\dfrac{5}{6}=\dfrac{18}{48}-\dfrac{40}{48}=-\dfrac{22}{48}=-\dfrac{11}{24}\)

b) \(\dfrac{-8}{18}-\dfrac{15}{27}=\dfrac{-24}{54}-\dfrac{30}{54}=\dfrac{-54}{54}=-1\)

c) \(\dfrac{2}{21}-\dfrac{-1}{28}=\dfrac{8}{84}-\dfrac{-3}{84}=\dfrac{11}{84}\)

I am not keen on listening to loud music
Jenny is not fond of doing housework
I am really interested in reading book 
She doesn't like watching films on TV
No, they didn't
Until the programs finished
Yes. they did
Life is much more comfortable
T - T

a. Ta có: \(\widehat{BHD}=\widehat{BCD}=90^o\)

\(\Rightarrow\) BHCD là tứ giác nội tiếp

b. Xét \(2\Delta\) vuông: \(\Delta BCK\) và \(\Delta DHK\) có:

\(\left\{{}\begin{matrix}\widehat{DHK}=\widehat{BCK}=90^o\\\widehat{HKC}.chung\end{matrix}\right.\)

\(\Rightarrow\Delta BCK\sim\Delta DHK\)

\(\Rightarrow\dfrac{CK}{BC}=\dfrac{HK}{DK}\Leftrightarrow CK.DK=HK.BC\)

:)))

.-. lớp 1 học số thập phân r hả

;))

gợi lên điều là mẹ đang dần hiện về