`4928:44=112`

`10650:75=142`

`15750:42=375`

`10725:25=429`

cãi nhau kinh thế :V

\(\dfrac{12}{13}\times\dfrac{2}{5}+\dfrac{4}{5}\times\dfrac{4}{13}+\dfrac{8}{26}+3:\dfrac{13}{4}\\ =\dfrac{4}{13}\times3\times\dfrac{2}{5}+\dfrac{4}{5}\times\dfrac{4}{13}+\dfrac{4}{13}\times\dfrac{2}{2}+3\times\dfrac{4}{13}\\ =\dfrac{4}{13}\times\dfrac{6}{5}+\dfrac{4}{5}\times\dfrac{4}{13}+\dfrac{4}{13}\times1+3\times\dfrac{4}{13}\\ =\dfrac{4}{13}\times\left(\dfrac{6}{5}+\dfrac{4}{5}+1+3\right)\\ =\dfrac{4}{13}\times6\\ =\dfrac{24}{13}\)

\(\dfrac{2x-5}{6}+\dfrac{22-7x}{4}>\dfrac{5-2}{3}-x-\dfrac{5x+2}{4}\\ \Leftrightarrow\dfrac{2\left(2x-5\right)}{6.2}+\dfrac{3\left(22-7x\right)}{4.3}>\dfrac{3.4}{3.4}-\dfrac{12.x}{12}-\dfrac{3\left(5x+2\right)}{3.4}\\ \Leftrightarrow\dfrac{4x-10}{12}+\dfrac{66-21x}{12}>\dfrac{12}{12}-\dfrac{12x}{12}-\dfrac{15x+6}{12}\\ \Leftrightarrow4x-10+66-21x>12-12x-15x-6\\ \Leftrightarrow-17x+56>6-27x\\ \Leftrightarrow-17x+56-6+27x>0\\ \Leftrightarrow10x+50>0\\ \Leftrightarrow10x>-50\\ \Leftrightarrow x>-5\)

Vậy bpt có nghiệm `x> -5`

sai r a

`a, 3-2x <= 15-5x`

`<=>3-2x-15+5x <= 0`

`<=>3x-12 <= 0`

`<=>3x <= 12`

`<=> x <= 4`

`3-2x<7`

`<=>2x>3-7`

`<=>2x > -4`

`<=>x > -2`

`b,` Để `x` nguyên thỏa mãn đồng thời cả hai bpt trên thì:

`-2 < x <= 4`

`<=>x∈{-1;0;1;2;3;4}`

\(\dfrac{2x-5}{6}+\dfrac{22-7x}{4}>\dfrac{5-2}{3}-x-\dfrac{5x+2}{4}\\ \Leftrightarrow\dfrac{2\left(2x-5\right)}{6.2}+\dfrac{3\left(22-7x\right)}{4.3}>\dfrac{3.4}{3.4}-\dfrac{12.x}{12}-\dfrac{3\left(5x+2\right)}{3.4}\\ \Leftrightarrow\dfrac{4x-10}{12}+\dfrac{66-21x}{12}>\dfrac{12}{12}-\dfrac{12x}{12}-\dfrac{15x+6}{12}\\ \Leftrightarrow4x-10+66-21x>12-12x-15x-6\\ \Leftrightarrow-17x+56>6-27x\\ \Leftrightarrow-17x+56-6+27x>0\\ \Leftrightarrow10x+50>0\\ \Leftrightarrow10x>-50\\ \Leftrightarrow x>-5\)

Vậy bpt có nghiệm `x > -5`

`A=x^2 -4x+1`

`=(x^2 -4x+4)-3`

`=(x-2)^2 -3`

Vì `(x-2)^2 >= 0 => (x-2)^2 -3 >= 0-3=-3`

Dấu "=" xảy ra `<=>x-2=0<=>x=2`

Vậy `A_(min) =-3<=>x=2`