gọi số gói 5 lạng là a; 2 lạng là b; 1 lạng là c
có: c=3b; a+b+c=24.
Có: 5*a+2*b+c=45
=>5*a+2*b+3*b=45
=>5*a+5*b=45
=>a+b=9
=> c=15 => b=5; a=4
1: \(\dfrac{2\cdot\left(x+2\right)}{3}-\dfrac{5\cdot\left(x-1\right)}{4}=\dfrac{3\cdot\left(5-x\right)}{2}-1\dfrac{1}{2}\cdot\left(2x+3\right)\)
1: \(\left(x-2\right)^2-2\cdot\left(x+1\right)^2=\left(2x+1\right)\cdot\left(1-3x\right)-2x\cdot\left(1-x\right)\)
1, \(4x-2\cdot\left\{x-3\left[2\cdot\left(1-2\right)-3\cdot\left(2x-1\right)\right]\right\}=4-2\left(1-x\right)\)
2, gọi O là 1 điểm của đoạn thẳng AB=4. xác định vị trí O để
a) AB + BO nhỏ nhất
b) AB + BO= 2BO
c) AB + BO = 3130
Bài 1: Tìm x a) \(\frac{1}{7}\cdot\left|x\right|-\frac{4}{5}=\frac{1}{5}\) b) \(\left(\frac{3}{4}-x\right)^3=-27\) c) \(\frac{x-1}{-2}=\frac{-8}{x-1}\) d) \(\left|2x-3\right|+4\cdot\left(-5\right)^2=101\)
4,Tìm x biết
a,\(\frac{-2}{3}\cdot x+\frac{1}{5}=\frac{3}{10}\)
b,\(\frac{2}{3}\cdot x-\frac{3}{2}\cdot x=\frac{5}{12}\)
c,\(\left(4,5-2x\right)\cdot\left(-1\frac{4}{7}\right)=\frac{11}{14}\)
d,\(\frac{1}{4}+\frac{1}{3}:3x=-5\)
e,\(\left(2\frac{4}{5}x-50\right):\frac{2}{3}=51\)
g,\(|4x-1|=\left(-3^2\right)\)
h,\(|x+70|=2\frac{1}{5}\)
i,\(\left(x-1^3\right)=125\)
k,\(\left(x+\frac{1}{2}\right)\cdot\left(\frac{2}{3}-2x\right)=0\)
Giúp mình nhé!!!
1: \(15-\left\{2\cdot\left[x-\left(2x-4\right)\cdot5\right]\cdot3\cdot\left(x+1\right)\right\}=12-x\)
1/S=\(\left(1+\dfrac{1}{2}\right)\cdot\left(1+\dfrac{1}{3}\right)\cdot\left(1+\dfrac{1}{4}\right)\cdot...\cdot\left(1+\dfrac{1}{100}\right)\)
2/B=\(\left(1-\dfrac{1}{2}\right)\cdot\left(1-\dfrac{1}{3}\right)\cdot\left(1-\dfrac{1}{4}\right)\cdot...\cdot\left(1-\dfrac{1}{2007}\right)\)
3/C=\(\dfrac{2^2}{1\cdot3}\cdot\dfrac{3^2}{2\cdot4}\cdot\dfrac{4^2}{3\cdot5}\cdot...\cdot\dfrac{100^2}{99\cdot101}\)
Bài 1: Tính a) \(\left(\frac{11}{12}:\frac{44}{16}\right)\cdot\left(\frac{-1}{3}+\frac{1}{2}\right)\) b) \(\frac{\left(-5^2\right)\cdot\left(-5\right)^3\cdot16}{5^4\cdot\left(-2\right)^4}\) c) \(7,5:\left(\frac{-5}{3}\right)+2\frac{1}{2}:\left(\frac{-5}{3}\right)\)d) \(\left(\frac{-1}{2}+\frac{1}{3}\right)\cdot\frac{4}{5}+\left(\frac{2}{3}+\frac{1}{2}\right):\frac{4}{5}\)
Bài 1:
1. Tính: \(E=1+\frac{1}{2}\left(1+2\right)+\frac{1}{3}\left(1+2+3\right)+\frac{1}{4}\left(1+2+3+4\right)+...+\frac{1}{200}\left(1+2+...+200\right)\)
2. Tìm và tính tổng các số nguyên x thỏa mãn: \(\frac{21}{5}\left|x\right|< 2019\)
3. Tìm x, biết: \(\frac{2^{24}\left(x-3\right)}{\left(3\frac{5}{7}-1,4\right)\left(6\cdot2^{24}-4^{13}\right)}=\left(\frac{5}{3}\right)^2\)
