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x.3,7+x.6,3=120b,x.3,7+x.6,3=120
x(3,7+6,3)=120x(3,7+6,3)=120
10x=12010x=120
x=120:10x=120:10
x=12(tm)
(15×24-x):0.25=100 : 1/4
(15×24-x):0.25 = 400
(15x24-x) = 100
360-x =100
x=260
(8.75+1.25 +5+1) x X=20
16 x X=20
X=20 :16
X=1.25
\(\left(84,6-2\cdot x\right):3,02=5,1\)
\(\Rightarrow84,6-2\cdot x=15,402\)
\(\Rightarrow2\cdot x=69,198\)
\(\Rightarrow x=69,198:2\)
\(\Rightarrow x=34,599\)
_____________
\(\left(15\cdot24-x\right):0,25=100:0,25\)
\(\Rightarrow\left(360-x\right):0,25=400\)
\(\Rightarrow360-x=100\)
\(\Rightarrow x-360-100\)
\(\Rightarrow x=260\)
______________
\(128\cdot x-12\cdot x-16\cdot x=5200\)
\(\Rightarrow x\cdot\left(128-12-16\right)=5200\)
\(\Rightarrow x\cdot100=5200\)
\(\Rightarrow x=5200:100\)
\(\Rightarrow x=52\)
__________________
\(5\cdot x+3,75\cdot x+1,25\cdot x=20\)
\(\Rightarrow x\cdot\left(5+3,75+1,25\right)=20\)
\(\Rightarrow10\cdot x=20\)
\(\Rightarrow x=20:10\)
\(\Rightarrow x=2\)
\(x\cdot3,7+x\cdot6,3=360:120\)
\(\Rightarrow x\cdot\left(3,7+6,3\right)=3\)
\(\Rightarrow x\cdot10=3\)
\(\Rightarrow x=\dfrac{3}{10}\)
__________________
\(x\cdot23-6\cdot23+x\cdot69=320\)
\(\Rightarrow x\cdot\left(23+69\right)=320+6\cdot23\)
\(\Rightarrow x\cdot92=458\)
\(\Rightarrow x=458:92\)
\(\Rightarrow x=\dfrac{229}{46}\)
___________________
\(\left(x+1\right)\left(x+2\right)=72\)
\(\Rightarrow x^2+2x+x+2=72\)
\(\Rightarrow x^2+3x+2=72\)
\(\Rightarrow x^2+3x+2-72=0\)
\(\Rightarrow x^2+3x-70=0\)
\(\Rightarrow x^2+10x-7x-70=0\)
\(\Rightarrow\left(x-7\right)\left(x+10\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=7\\x=-10\end{matrix}\right.\)
___________________
\(\left(x+2\right)\cdot16\cdot x=160x\)
\(\Rightarrow16x^2+32x=160x\)
\(\Rightarrow16x^2+32x-160x=0\)
\(\Rightarrow16x^2-128x=0\)
\(\Rightarrow16x\left(x-8\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=8\end{matrix}\right.\)
\(a,\) \(5.\left(4+6x\right)=290\)
\(4+6x=290:5\)
\(4+6x=58\)
\(6x=58-4\)
\(6x=54\)
\(x=54:6\)
\(x=9\left(tm\right)\)
Vậy ..................
\(b,x.3,7+x.6,3=120\)
\(x\left(3,7+6,3\right)=120\)
\(10x=120\)
\(x=120:10\)
\(x=12\left(tm\right)\)
Vậy ....................
c) \(\left(15.24-x\right):0,25=100:\dfrac{1}{4}\)
\(\left(360-x\right):\dfrac{1}{4}=400\)
\(360-x=400.\dfrac{1}{4}\)
\(360-x=100\)
\(x=360-100\)
\(x=260\left(tm\right)\)
Vậy ...................
a) 5. ( 4+6 . x ) = 290
( 4+6 . x ) = 290 : 5
4 + 6 . x = 58
6 .x = 58 - 4
6.x = 54
x = 54 : 6
x = 9
| x + 4/15 | - | - 3,75 | = - | - 2,15 |
| x + 4/15 | - 3,75 = - 2,15
| x + 4/15 | = - 2,15 + 3,75
| x + 4/15 | = 1,6
Trường hợp 1 : x + 4/15 = 1,6 suy ra x = 4/3
Trương hợp 2: x + 4/15 = - 1,6 suy ra x = -28/15
\(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\Rightarrow\left|x+\frac{4}{15}\right|-3,75=-2,15\)
\(\Rightarrow\left|x+\frac{4}{15}\right|=-2,15+3,75\)
\(\Rightarrow\left|x+\frac{4}{15}\right|=1,6\)
\(\Rightarrow\left|x+\frac{4}{15}\right|=\frac{8}{5}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x+\frac{4}{15}=\frac{8}{5}\\x+\frac{4}{15}=-\frac{8}{5}\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=\frac{4}{3}\\x=-\frac{28}{15}\end{array}\right.\)
Ta có : \(\left|x+\frac{4}{15}\right|-\left|-3,75\right|=-\left|-2,15\right|\)
\(\Leftrightarrow\left|x+\frac{4}{15}\right|=3,75-2,15=\frac{8}{5}\)
\(\Rightarrow\left[\begin{array}{nghiempt}x+\frac{4}{15}=\frac{8}{5}\\-x-\frac{4}{15}=\frac{8}{5}\end{array}\right.\)
\(\Leftrightarrow\left[\begin{array}{nghiempt}x=\frac{4}{3}\\x=-\frac{28}{15}\end{array}\right.\)
a) Vì I3,7 - xI có GTNN = 0 => x = 0 (để I3,7 - xI có GTNN) => GTNN của I3,7 - xI + 2,5 là 2,5
b) Cách giải giống câu trên . KQ : -4,5
\(\dfrac{7011}{25}:\left(x-42.6\right).15=13\)
\(\Rightarrow\dfrac{7011}{\dfrac{25}{\left(x-42,6\right)}}.0,15=13\)
\(\Rightarrow\dfrac{280,44}{\left(x-42,6\right)}.0,15=13\)
\(x-\left(280,44-42,6\right)\)
\(x=237.8+86,7\)
\(x=324,54\)
\(\)Vậy x=324,54
b.
\(7,2-\left(x+3,75:2,1\right):1,9=5,2\)
\(\Rightarrow7,2+\dfrac{-\left(x-\dfrac{3,75}{2,1}\right)}{1,9}=5,2\)
\(7,2+\dfrac{-\left(x-1,8\right)}{1,9}=5,2\)
13,44 . x - (1,6 + x) . 0,5 - 3,7 . (x - 0,9) =13,618
=> 13,44x - 0,8 - 0,5x - 3,7x + 3,33 - 13,618 = 0
=> 9,24x - 11,088 = 0
=> 9,24x = 11,088
=> x = 1,2
13,44 . x - (1,6 + x) . 0,5 - 3,7 . (x - 0,9) =13,618
=> 13,44x - 0,8 - 0,5x - 3,7x + 3,33 - 13,618 = 0
=> 9,24x - 11,088 = 0
=> 9,24x = 11,088
=> x = 1,2
=>3,75x=3,75x2,1
=>x=2,1
2,1 x 3,75 =X x (0,05+3,7)
2,1 x 3,75 =X x 3,75
X x 3,75 = 2,1 x 3,75
X x 3,75 = 7,875
X = 7,875 : 3,75
X = 2,1