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a) 3/5 x=4/7+1/5; b)(2x-1/2):3=12;
3/5 x=27/35 (2x-1/2)=12x3
x=27/35:3/5 2x-1/2=36
x=9/7 2x=36+1/2
Vay x=9/7 2x=73/2
x=73/2:2
x=73/4
Vay x=73/4
a, (10/3:x).(-5/4)=-10/3
10/3:x=-10/3:(-5/4)
10/3:x=8/3
x=10/3:8/3
x=5/4
b,(-6/5+x):(-18/5)=-1/4
-6/5+x=-1/4.(-18/5)
-6/5+x=9/10
x=9/10-(-6/5)=9/10+6/5
x=21/10
c,-22/15.x+1/3=-2/5
-22/15.x=-2/5-1/3=-11/15
x=-11/15:(-22/15)
x=11/21
d,(0,25-30%x).1/3=-31/6+1/4=-59/12
1/4-3/10x=-59/12:1/3=-59/4
3/10x=1/4-(-59/4)=1/4+59/4=15
x=15:3/10
x=50
e,(0,5x-3/7):1/2=8/7
1/2x=8/7.1/2=4/7
x=4/7:1/2
x=8/7
a, \(x\) \(\times\) \(\dfrac{1}{2}\) - \(\dfrac{3}{4}\) = \(\dfrac{5}{6}\)
\(x\) \(\times\) \(\dfrac{1}{2}\) = \(\dfrac{5}{6}\) + \(\dfrac{3}{4}\)
\(x\) \(\times\) \(\dfrac{1}{2}\) = \(\dfrac{19}{12}\)
\(x\) = \(\dfrac{19}{12}\) : \(\dfrac{1}{2}\)
\(x\) = \(\dfrac{19}{6}\)
b, \(x\) : \(\dfrac{1}{2}\) - \(\dfrac{3}{4}\) = \(\dfrac{5}{6}\)
\(x\): \(\dfrac{1}{2}\) = \(\dfrac{5}{6}\) + \(\dfrac{3}{4}\)
\(x\) : \(\dfrac{1}{2}\) = \(\dfrac{19}{12}\)
\(x\) = \(\dfrac{19}{12}\) \(\times\) \(\dfrac{1}{2}\)
\(x\) = \(\dfrac{19}{24}\)
c, \(x\) \(\times\) \(\dfrac{3}{4}\) + \(x\) \(\times\) \(\dfrac{1}{4}\) = \(\dfrac{7}{8}\)
\(x\) \(\times\) ( \(\dfrac{3}{4}\) + \(\dfrac{1}{4}\)) = \(\dfrac{7}{8}\)
\(x\) \(\times\) 1 = \(\dfrac{7}{8}\)
\(x\) = \(\dfrac{7}{8}\)
d, \(x\times\) \(\dfrac{3}{4}\) - \(x\) \(\times\) \(\dfrac{1}{4}\) = \(\dfrac{7}{8}\)
\(x\) \(\times\) ( \(\dfrac{3}{4}\) - \(\dfrac{1}{4}\)) = \(\dfrac{7}{8}\)
\(x\) \(\times\) \(\dfrac{1}{2}\) = \(\dfrac{7}{8}\)
\(x\) = \(\dfrac{7}{8}\) : \(\dfrac{1}{2}\)
\(x\) = \(\dfrac{7}{4}\)
Bài 2:
B=1+(-2)+3(-4)+5+(-6)+......+99+(-100)
B= (1+3+5+...+99)+[(-2)+(-4)+...+(-100)]
B= (1+3+5+...+99)-(2+4+...+100)
Đặt M=(1+3+5+...+99) ; N= (2+4+...+100)
+) M=1+3+5+...+99
Ta có 2 số kề nhau cách nhau 2đv
Số các số hạng = (99-1):2+1=50 số
Tổng M = (99+1).50:2=2500
+) Tương tự tổng N= 2450
Vậy B= M-N = 2500-2450= 50
Tk nhé!!
nhiều quá :((
\(a,2\left(x-5\right)-3\left(x+7\right)=14\)
\(2x-10-3x-21=14\)
\(-x-31=14\)
\(-x=45\)
\(x=45\)
\(b,5\left(x-6\right)-2\left(x+3\right)=12\)
\(5x-30-2x-6=12\)
\(3x-36==12\)
\(3x=48\)
\(x=16\)
\(c,3\left(x-4\right)-\left(8-x\right)=12\)
\(3x-12-8+x=0\)
\(4x-20=0\)
\(4x=20\)
\(x=5\)
Cố nốt nha bn !
cảm ơn, bn nha:)))
mà hình như bạn TOP 3 trả lời câu hỏi pải ko nhỉ???
cái chữ này cj nhìn khó hiểu quá nên em thông cảm nếu muốn bt đáp án thì viết rõ ra đc chứ^^
\(a)\dfrac{x}{3}=\dfrac{3}{2}.\dfrac{1}{4}\)
\(\dfrac{x}{3}=\dfrac{3}{8}\)
\(8x=9\)
\(x=\dfrac{9}{8}\)
__________________________________________
\(b)\dfrac{x}{5}=\dfrac{-1}{3}:\dfrac{7}{2}\)
\(\dfrac{x}{5}=\dfrac{-2}{21}\)
\(21x=-10\)
\(x=\dfrac{-10}{21}\)
__________________________________________
\(c)x+\dfrac{2}{3}=\dfrac{4}{3}-\dfrac{1}{6}\)
\(x+\dfrac{2}{3}=\dfrac{7}{6}\)
\(x=\dfrac{7}{6}-\dfrac{2}{3}\)
\(x=\dfrac{1}{2}\)
__________________________________________
\(d)x-\dfrac{5}{2}=\dfrac{7}{2}-4\)
\(x-\dfrac{5}{2}=\dfrac{-1}{2}\)
\(x=\dfrac{-1}{2}+\dfrac{5}{2}\)
\(x=2\)
a) \(\dfrac{x}{3}=\dfrac{3}{2}\cdot\dfrac{1}{4}\)
\(\dfrac{x}{3}=\dfrac{3}{8}\)
\(x=\dfrac{3\cdot3}{8}\)
\(x=\dfrac{9}{8}\)
b) \(\dfrac{x}{5}=\dfrac{-1}{3}:\dfrac{7}{2}\)
\(\dfrac{x}{5}=\dfrac{-1}{3}\cdot\dfrac{2}{7}\)
\(\dfrac{x}{5}=\dfrac{-2}{21}\)
\(x=\dfrac{-2\cdot5}{21}\)
\(x=-\dfrac{10}{21}\)
c) \(x+\dfrac{2}{3}=\dfrac{4}{3}-\dfrac{1}{6}\)
\(\dfrac{6x}{6}+\dfrac{2\cdot2}{3\cdot2}=\dfrac{4\cdot2}{3\cdot2}-\dfrac{1}{6}\)
\(\dfrac{6x}{6}+\dfrac{4}{6}=\dfrac{8}{6}-\dfrac{1}{6}\)
\(\dfrac{6x+4}{6}=\dfrac{7}{6}\)
\(\dfrac{6x+4}{6}-\dfrac{7}{6}=0\)
\(\dfrac{6x+4-7}{6}=0\)
\(\dfrac{6x-3}{6}=0\)
\(6x-3=0\)
\(6x=3\)
\(x=\dfrac{3}{6}=\dfrac{1}{2}\)