\(35\cdot34+70\cdot38+65\cdot75+65\cdot35\)

\(=35\cdot34+35\cdot76+65\cdot\left(75+35\right)\)

\(=35\cdot\left(34+76\right)+65\cdot110\)

\(=35\cdot110+65\cdot110\)

\(=110\cdot\left(65+35\right)\)

\(=110\cdot100=11000\)

35 . 34 + 70 . 38 + 65 . 75 + 65 . 35

= 35 . 34 + 35 . 76 + 65 . 75 + 65 . 35

= 35 . (34 + 76) + 65 . (75 + 35)

= 35 . 110 + 65 . 110

= 110 . (35 + 65)

= 110 . 100

= 11000

~Std well~

\(35\cdot34+70\cdot38+65\cdot75+65\cdot35\)

\(=35\cdot34+35\cdot76+65\cdot75+65\cdot35\)

\(=35\cdot\left(34+76\right)+65\cdot\left(75+35\right)\)

\(=35\cdot110+65\cdot110\)

\(=110\cdot\left(35+65\right)\)

\(=110\cdot100=11000\)

225/143 nha ban

158692,1211

225/143

\(\Rightarrow12+20x-60=45x-15\Leftrightarrow25x=-33\Leftrightarrow x=-\dfrac{33}{25}\)

12+20x−60=45x−15

25x=−33

x=−\(\dfrac{33}{25}\)

\(\dfrac{3+5x}{5}-3=\dfrac{9x-3}{4}\)

\(\Leftrightarrow\dfrac{5x-12}{5}=\dfrac{9x-3}{4}\)

\(\Leftrightarrow20x-48=45x-15\)

\(\Leftrightarrow25x=-33\)

\(\Leftrightarrow x=-\dfrac{33}{25}\)

\(f,=\left(5^2+3\right):7=28:7=4\\ g,=7^2-9+8\cdot25=49-9+200=240\\ h,=600+72+18=690\\ i,=5^2+5-20=10\\ j,=45-28+83=100\)

\(2A=\frac{4}{1.5}+\frac{6}{5.11}+\frac{8}{11.19}+\frac{10}{19.29}+\frac{12}{29.41}\)

\(=1-\frac{1}{5}+\frac{1}{5}-\frac{1}{11}+\frac{1}{11}-\frac{1}{19}+...+\frac{1}{29}-\frac{1}{41}=1-\frac{1}{41}=\frac{40}{41}\)

\(\Rightarrow A=\frac{20}{21}\)

\(3B=\frac{3}{1.4}+\frac{6}{4.10}+\frac{9}{10.19}+\frac{12}{19.31}=1-\frac{1}{4}+\frac{1}{4}-\frac{1}{10}+\frac{1}{10}-\frac{1}{19}+\frac{1}{19}-\frac{1}{31}\)

\(=1-\frac{1}{31}=\frac{30}{31}\)

\(\Rightarrow B=\frac{10}{31}=\frac{20}{62}<\frac{20}{41}\)

Do đó $A>B$

Ta có: \(A=\dfrac{2}{1.5}+\dfrac{3}{5.11}+\dfrac{4}{11.19}+\dfrac{5}{19.29}+\dfrac{6}{29.41}\)

\(2A=1-\dfrac{1}{5}+\dfrac{1}{5}+...+\dfrac{1}{29}-\dfrac{1}{41}\)

\(2A=1-\dfrac{1}{41}=\dfrac{40}{41}\)

\(A=\dfrac{20}{41}\)

Lại có: \(B=\dfrac{1}{1.4}+\dfrac{2}{4.10}+\dfrac{3}{10.19}+\dfrac{4}{19.31}\)

\(3B=\dfrac{3}{1.4}+\dfrac{6}{4.10}+\dfrac{9}{10.19}+\dfrac{12}{19.31}\)

\(3B=1-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{10}+...+\dfrac{1}{19}-\dfrac{1}{31}\)

\(3B=1-\dfrac{1}{31}=\dfrac{30}{31}\)

\(B=\dfrac{10}{31}\)

Vì \(\dfrac{20}{41}>\dfrac{10}{31}\) nên...

đk : \(n\ne-\dfrac{1}{3}\)

gọi d là ƯCLN(18n+3,21n+7)

ta có 18n+3chia hết cho d

          21n+7 chia hết cho d

⇔21n+7-18n-3 chia hết cho d

⇔126n+42-126n-21 chia hết cho d 

21 chia hết cho d

⇒d∈Ư(21)=1;3;7;21

n ≠ 3k-1;3k-3;3k-7;3k-21

=7 x 2 x 8 + 7 x 9 + 7 x 75 

=7 x 16     + 7 x 9 + 7 x 75

=7 x (16 + 9 + 75)

=7 x 100

=700

tk đi 

mik tk lại ok:):):)

7.2.8+7.9+7.75

=7.16+7.9+7.75

=7.(16+9+75)

=7.100

=700

14.8+7.9+7.75

=7.2.8+7.9+7.75

=7(16+9+75)

=7.100

=700

k nhé xong mình k lại

umm..đề bài đâu bn?

Đề bài pay mất r bn<3

0,35 × 135 - 35% × 35

= 0,35 × 135 - 0,35 × 35

= 0,35 × (135 - 35)

= 0,35 × 100

= 35

\(0,35\times135-35\%\times35\)

\(=0,35\times135-0,35\times35\)

\(=0,35\times\left(135-35\right)\)

\(=0,35\times100\)

\(=35\)

bạn Linh và Phong ơi nếu hai bạn rảnh thì giúp mik 1 bài  nữa được ko  

các bạn vào trang cá nhân của mik thấy câu có 50 % thì giúp mik với nhé