X x 11 = X x 90
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sai đề
(x+1 ) + (x+3)+..........+(x+99)=0
=> x + 1 + x + 3 + x + 5 + ........... + x + 99 = 0
Từ 1-->99 có số số hạng là:
(99-1):2+1=50(số)
Tổng từ 1 -->99 là:
(99+1) x 50:2=2500
=> 50x + 2500=0
=>50x=-2500
=>x=-50
Câu 2 mình k hiểu đề
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90 + 90 = 180
2 x 2 = 4
9 x 9 = 81
8 x 8 = 64
200 x 1860 = 336 000
89 x 22 = 1958
88 x 11 = 968
1980 x 1980 + 1980 x 2980 = 9 820 800
20000 x 400 = 8 000 000
9960 x 2235 = 22 260 600
90 + 90 = 180
2 x 2 = 4
9 x 9 = 81
8 x 8 = 64
200 x 1860 = 372000
89 x 22 = 1958
88 x 11 = 968
1980 x 1980 + 1980 x 2980 = 9820800
20000 x 400 = 8000000
9960 x 2235 =22260600
k mik nha
chúc bạn hok giỏi
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\(\frac{11}{15}-\left(\frac{7}{9}+x\right).\frac{3}{8}=\frac{61}{90}+\frac{x}{3}\)(. là dấu nhân)
\(\Leftrightarrow\frac{11}{15}-\frac{7}{24}-\frac{3x}{8}-\frac{61}{90}-\frac{x}{3}=0\)
\(\Leftrightarrow\frac{-17}{72}-\left(\frac{3x}{8}+\frac{x}{3}\right)=0\)
\(\Leftrightarrow\frac{17x}{24}=-\frac{17}{72}\)
\(\Leftrightarrow17x.72=-17.24\)
\(\Leftrightarrow x=-\frac{1}{3}\)
\(\frac{11}{15}-\left(\frac{7}{9}+x\right).\frac{3}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{11}{15}-\frac{7}{9}.\frac{3}{8}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{11}{15}-\frac{7}{24}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{53}{120}-\frac{3x}{8}=\frac{61}{90}+\frac{x}{3}\)
\(\Rightarrow\frac{53}{120}-\frac{61}{90}=\frac{8x+9x}{24}\)
\(\Rightarrow-\frac{17}{72}=\frac{17x}{24}\)
\(\Rightarrow\frac{-17}{72}.24=17x\)
\(\Rightarrow-17.3=17x\Leftrightarrow x=-3\)
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Ta có : (x+1)/99+(x+2)/98=(x+3)/97+(x+4)/96
->(x+1)/99+1+(x+2)/98+1=(x+3)/97+1+(x+...
->(x+100)/99+(x+100)/98=(x+100)/97+(x+...
->(x+100)*(1/99+1/98-1/97-1/96)
mà (1/99+1/98-1/97-1/96 khác 0
nên x+100=0
-> x=-100
p/s:tham khaor
:3)))
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câu 1
=> x+1/2+x+1/3+x+1/4-x-1/5-x-1/6=0
=> (x+x+x-x-x)+(1/2+1/3+1/4-1/5-1/6)=0
=> x+43/60=0
=> x = -43/60
câu dưới làm tương tự bạn nhé!
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a) 91 - x = 90
x = 91 - 90
x = 1
b) x - 73.21 = 73.26
x = 73.26 + 73.21
x = 73.(26 + 21)
x = 73.47
x = 3431
c) 6.(x + 11) = 0
x + 11 = 0 : 6
x + 11 = 0
x = 0 - 11
x = -11
d) 2x - 12 - x = 9
=> 2x - (12 + 9) = x
=> (2 - 1)x = 21
=> x = 21
Ta có:
Xx11=X+90
=> Xx10=90
=> x=9