Tìm x: (hứa tick)
a) 4/X = 2/9
b) X x 0,3 = 3/5
c) X : 1,1 = 3/4
d) 121,8 : X = 5/9
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a) \(\dfrac{4}{x}=\dfrac{2}{9}\)
\(x=\dfrac{\left(4\times9\right)}{2}\)
\(x=\dfrac{36}{2}\)
\(x=18\)
b) \(x\times0,3=\dfrac{3}{5}\)
\(x\times\dfrac{3}{10}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{3}{10}\)
\(x=\dfrac{3}{5}\times\dfrac{10}{3}\)
\(x=\dfrac{30}{15}\)
\(x=2\)
c) \(1,1=\dfrac{3}{4}\) câu này thiếu
d) \(121,8:x=\dfrac{5}{9}\)
\(\dfrac{609}{5}:x=\dfrac{5}{9}\)
\(x=\dfrac{609}{5}:\dfrac{5}{9}\)
\(x=\dfrac{609}{5}\times\dfrac{9}{5}\)
\(x=\dfrac{5481}{25}\)
a, (27,5 x 0,1 + 2,5 x 0,1) x 2
=(0,1 x (2,5+27,5)) x 2
=(0,1 x 30) x 2
=3 x 2
=6
b, 82,37 + 36 + 63 x 82,37 + 82,37
Khó quá ! chắc bạn chép sai đề
c, (27,54 x 1,1 - 279,24 x 0,1) : 0,3
hình nhưu lại sai đề
a)\(\dfrac{2}{3}.\dfrac{4}{5}+\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}+\dfrac{1}{3}\right).\dfrac{4}{5}=1.\dfrac{4}{5}=\dfrac{4}{5}\)
b)\(\dfrac{2}{3}.\dfrac{4}{5}-\dfrac{1}{3}.\dfrac{4}{5}=\left(\dfrac{2}{3}-\dfrac{1}{3}\right).\dfrac{4}{5}=\dfrac{1}{3}.\dfrac{4}{5}=\dfrac{4}{15}\)
a) \(\dfrac{2}{3}\times\dfrac{4}{5}+\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}+\dfrac{1}{3}\right)=\dfrac{4}{5}\times1=\dfrac{4}{5}\)
b) \(\dfrac{2}{3}\times\dfrac{4}{5}-\dfrac{1}{3}\times\dfrac{4}{5}=\dfrac{4}{5}\times\left(\dfrac{2}{3}-\dfrac{1}{3}\right)=\dfrac{4}{5}\times\dfrac{1}{3}=\dfrac{4}{15}\)
c) \(\dfrac{1}{2}:\dfrac{3}{4}+\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}+\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\times\left(\dfrac{1}{2}+\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{2}{3}=\dfrac{8}{9}\)
d) \(\dfrac{1}{2}:\dfrac{3}{4}-\dfrac{1}{6}:\dfrac{3}{4}=\dfrac{1}{2}\times\dfrac{4}{3}-\dfrac{1}{6}\times\dfrac{4}{3}=\dfrac{4}{3}\left(\dfrac{1}{2}-\dfrac{1}{6}\right)=\dfrac{4}{3}\times\dfrac{1}{3}=\dfrac{4}{9}\)
a) x : 1/4 = 7/5
x = 7/5 x 1/4
x = 7/20
b) 9/2 - x = 3/5
x = 9/2 - 3/5
x = 39/10
c) 12/5 : x = 7/2
x = 12/5 : 7/2
x = 24/35
OK
1. 1/2-(x-1/4)=1/3
=> x-1/4=1/2-1/3
=> x-1/4= 1/6
=> x= 1/6+1/4=5/12
2. 3/2*(x-1/2-1)=5/4
=> x-1/2-1=5/4:3/2
=> x-1/2= 5/6+1
=> x = 11/6+1/2
=> x= 7/3
3. 11/2-9/2*(x-3/4)=1
=> 9/2*(x-3/4)= 11/2-1
=> x-3/4 = 9/2:9/2
=> x= 1+3/4
=> x= 7/4
Chúc bạn Hk tốt!!!!!
1. x=\(\frac{5}{12}\)
2. x=\(\frac{7}{3}\)
3. x= \(\frac{7}{4}\)
Chúc bạn Hk tốt!!!
a) x2 +x +1 = x2 + x + 1/4 + 3/4 =(x+1/2)2 + 3/4
=> GTNN a) =3/4 khi x=-1/2
b) 4x2 +4x -5 = 4x2 + 4x +1 -6 = (2x+1)2-6
=> GTNN b) = -6 khi x=-1/2
c) (x-3)(x+5) +4 = x2+2x -11 = x2+2x +1-12=(x+1)2-12
GTNN c) =12 khi x=-1
d) x2-4x+y2-8y+6=x2-4x+4+y2-8y+16-14=(x-2)2+(y-4)2-14
GTNN d) =-14 khi x=2 , y=4
\(a,=\left(x^2+x+\dfrac{1}{4}\right)+\dfrac{3}{4}=\left(x+\dfrac{1}{2}\right)^2+\dfrac{3}{4}\ge\dfrac{3}{4}\)
Dấu \("="\Leftrightarrow x=-\dfrac{1}{2}\)
\(b,=\left(4x^2+4x+1\right)-6=\left(2x+1\right)^2-6\ge-6\)
Dấu \("="\Leftrightarrow x=-\dfrac{1}{2}\)
\(c,=x^2+2x-15+4=\left(x+1\right)^2-12\ge-12\)
Dấu \("="\Leftrightarrow x=-1\)
\(d,=\left(x^2-4x+4\right)+\left(y^2-8y+16\right)-14=\left(x-2\right)^2+\left(y-4\right)^2-14\ge-14\)
Dấu \("="\Leftrightarrow\left\{{}\begin{matrix}x=2\\y=4\end{matrix}\right.\)
a: =>x+7/4=6:2/3=9
=>x=29/4
b: =>x:5/3=7/5
=>x=7/5*5/3=7/3
c:=>x+1/6=5/3
=>x=10/6-1/6=3/2
d: =>x+4/5=4/5+3/7+3/5
=>x=3/7+3/5=36/35
e: =>x/35=4/5-5/7=3/35
=>x=3
f: =>13/28+x=1/2
=>x=1/28
g: =>1/3-x=1/9
=>x=2/9
tự làm là hạnh phúc của mỗi công dân.