x ⋮ (16, 15, 11) ⇔x ϵ BC(11, 15, 16) = { 2640; 5280; 7920;....}

vì x < 3000  ⇔ x = 2640

6x(x-5) + 2 (x-5) =0

2(x-5)(3x +1 ) =0

x- 5 = 0 hoặc 3x + 1 = 0

x = 5 , x = -1/3

(2x -1)² + (x + 8)² = không đủ dữ kiện

21 kg mì sợi nhé

21 kg nhe

là 1+1+11111111 đấy các bạn ạ

help me

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

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

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

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

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

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

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

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

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

Nhầm, đây mới đúng

\(385\times485+386\times515\)

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

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

\(=386\times1000-485\)

\(=386000-485=198660\)

\(385\times485+386\times515\)

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

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

\(=385\times1000+385\)

\(=385000+385\)

\(=385385\)