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a) \(\frac{22}{7}\div\left(11-\chi\right)=\frac{7}{5}-\frac{2}{3}\)
\(\frac{22}{7}\div\left(11-\chi\right)=\frac{11}{15}\)
\(\left(11-\chi\right)=\frac{22}{7}\div\frac{11}{15}\)
\(\left(11-\chi\right)=\frac{30}{7}\)
\(\chi=11-\frac{30}{7}\)
\(\chi=\frac{47}{7}\)
b) (x+1)+(x+2)+(x+3)+...+(x+100)=5550
Từ 1 đến 100 có 100 số hạng => Có 100 x
(x + x + x + .... + x) + (1 + 2 + 3 + .. + 100) = 5550
Áp dụng tính chất cộng dãy số cách đều, ta có
(100.x) + 5050 = 5550
100.x = 5550 - 5050
100.x = 500
x = 500 : 100
x = 5
\(71+65\cdot4=\frac{x+140}{x}+260\)
\(71+260=\frac{x+140}{x}+260\)
\(71=\frac{x}{x}+\frac{140}{x}\)
\(71=1+\frac{140}{x}\)
\(71-1=\frac{140}{x}\)
\(70=\frac{140}{x};\Rightarrow x=2\)
\(71+65\times4=\frac{x+140}{x}+260\)
\(71+260=\frac{x+140}{x}+260\)
\(71=\frac{x+140}{x}\)
\(\Rightarrow71x=x+140\)
\(\Rightarrow71x-x=140\)
\(\Rightarrow70x=140\)
\(\Rightarrow x=2\)
Lời giải:
a. $(x.0,25+1999).2000=(53+1999).2000$
$x.0,25.2000+1999.2000=53.2000+1999.2000$
$x.0,25.2000=53.2000$
$x.0,25=53$
$x=53:0,25=212$
b.
$(5457+x:2):7=1075$
$5457+x:2=1075\times 7=7525$
$x:2=7525-5457=2068$
$x=2068\times 2=4136$
c.
$1-(\frac{12}{5}+x-\frac{8}{9}): \frac{16}{9}=0$
$(\frac{12}{5}+x-\frac{8}{9}):\frac{16}{9}=1$
$\frac{12}{5}+x-\frac{8}{9}=1.\frac{16}{9}=\frac{16}{9}$
$\frac{68}{45}+x=\frac{16}{9}$
$x=\frac{16}{9}-\frac{68}{45}=\frac{4}{15}$
[ X x 0,25 + 1999 ] x 2000 = [ 53 + 1999 ] x2000
\(\Rightarrow\)x=212
[ X x 0,25 + 1999 ] x 2000 = [ 53+1999 ] x 2000
[ X x 0,25 + 1999 ] = [ 53+1999 ] x 2000 : 2000
X x 0,25 + 1999 = 53+1999
X x 0,25 = 53 + 1999 - 1999
X x 0,25 = 53
X = 53 : 0,25 =212
a) 3/x-7 = 27/135
3/x-7 = 3/15
x - 7 = 15
x = 15 + 7
x = 22
a) \(\frac{3}{x-7}=\frac{27}{135}\)
\(\Rightarrow\)\(\left(x-7\right).27=3.135\)
\(\Rightarrow\)\(\left(x-7\right).27=405\)
\(\Rightarrow\)\(x-7=15\)
\(\Rightarrow\)\(x=22\)
Vậy \(x=22\)
b ) \(71+65.4=\frac{x+140}{x}+260\)
\(71+260=\frac{x+140}{x}+260\)
\(331=\frac{x+140}{x}+260\)
\(331-260=\frac{x+140}{x}\)
\(71=\frac{x+140}{x}\)
\(71=\frac{x}{x}+\frac{140}{x}\)
\(71=1+\frac{140}{x}\)
\(70=\frac{140}{x}\)
\(x=140\div70\)
\(x=20\)
Vậy \(x=20\)
#TQY
a ) x - 5 \(\in\)B ( 6 )
\(\Rightarrow\)x - 5 \(\in\){ 0 ; 6 ; 12 ; 18 ; 24 ; 30 ; 36 ; 42 ; 48 ; ..... }
\(\Rightarrow\)x \(\in\){ 5 ; 11 ; 17 ; 23 ; 29 ; 35 ; 41 ; 47 ; 53 ; .... }
b ) x - 1 \(⋮\)4
\(\Rightarrow\)x - 1 \(\in\)B ( 4 )
\(\Rightarrow\)x - 1 \(\in\){ 0 ; 4 ; 8 ; 12 ; 16 ; 20 ; 24 ; 28 ; 32 ; 36 ; 40 ; ..... }
\(\Rightarrow\)x \(\in\){ 1 ; 5 ; 9 ; 13 ; 17 ; 21 ; 25 ; 29 ; 33 ; 37 ; 41 ; .... }
a)(x.0,25+1999)x2000=(53+1999)x2000
(x.0,25+1999)=53+1999
x.0,25=53
x=53x4
x=210
a)(x.0,25+1999)x2000=(53+1999)x2000
(x.0,25+1999)=53+1999
x.0,25=53
x=53x4
x=210
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