\(37\times25+37\times35+37\times39+37\)

\(=37\times\left(25+35+39+1\right)\)

\(=37\times100=3700\)

Để \(\dfrac{x-4}{x}\in Z\) thì \(x-4⋮x\)

\(\Rightarrow4⋮x\Rightarrow x\inƯ\left(4\right)=\left\{1;4;-1;-4\right\}\)

\(\Rightarrow x=\left\{1;4;-1;-4\right\}\)

1S

2Đ

3Đ

4Đ

5Đ

6S

7Đ

8Đ

9S

10S

2, Để \(\dfrac{8a+19}{4a+1}\in Z\) thì \(8a+19⋮4a+1\)

\(\Rightarrow8a+2+17⋮4a+1\)

mà \(8a+2⋮4a+1\) nên \(17⋮4a+1\)

\(\Rightarrow4a+1\inƯ\left(17\right)=\left\{1;-1;17;-17\right\}\)

Bn lập bảng nha

\(m:4+m:3+m:2=25\)

\(\Rightarrow\dfrac{1}{4}m+\dfrac{1}{3}m+\dfrac{1}{2}m=25\)

\(\Rightarrow m\left(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}\right)=25\)

\(\Rightarrow\dfrac{13m}{12}=25\Rightarrow m=\dfrac{300}{13}\)

Bn sửa kq nha, hôm nay hơi lag

Nhầm, đây mới đúng

\(385\times485+386\times515\)

\(=386\times485+386\times515-485\)

\(=386\left(485+515\right)-485\)

\(=386\times1000-485\)

\(=386000-485=198660\)

\(385\times485+386\times515\)

\(=385\times485+385\times515+385\)

\(=385\times\left(485+515\right)+385\)

\(=385\times1000+385\)

\(=385000+385\)

\(=385385\)

Có: \(28=2^2.7\)

\(56=2^4.7\)

\(72=2^3.3^2\)

\(ƯCLN\left(28;56;72\right)=2^2=4\)

\(D=-20\%:\left(-\dfrac{1}{2}\right)^2-\left(-1\right)^{2021}.2\dfrac{1}{3}-0,2\)

\(\Rightarrow D=-\dfrac{1}{5}:\dfrac{1}{4}+1.\dfrac{7}{3}-\dfrac{1}{5}\)

\(\Rightarrow D=-\dfrac{4}{5}+\dfrac{7}{3}-\dfrac{1}{5}\)

\(\Rightarrow D=-1+\dfrac{7}{3}=\dfrac{4}{3}\)