tim x
a. 25% × x = 42,6 - 3,28
b. x ÷ 40% = 7,25 + 6,75
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\(a,25\%x=42,6-3,28\\ \Leftrightarrow\dfrac{1}{4}x=39,32\\ \Leftrightarrow x=157,28\)
\(b,x:40\%=7,25+6,75\\ \Leftrightarrow x:40\%=14\\ \Leftrightarrow x=5,6\)
\(c,\dfrac{7011}{25}:\left(x-42,6\right)=117,14-47,03\\ \Leftrightarrow\dfrac{7011}{25}:\left(x-42,6\right)=70,11\\ \Leftrightarrow x-42,6=4\\ \Leftrightarrow x=46,6\)
\(d,0,3\left(x+\dfrac{1}{3}\right)=\dfrac{1}{2}\cdot\left(0,81:27\right)\\ \Leftrightarrow0,3\left(x+\dfrac{1}{3}\right)=0,015\\ \Leftrightarrow x+\dfrac{1}{3}=0,05\\ \Leftrightarrow x=-\dfrac{17}{60}\)
\(\left(25\%\cdot x-7,25\right)+4,25=10\)
=>\(x\cdot0,25-3=10\)
=>\(x\cdot0,25=13\)
=>\(x=\dfrac{13}{0,25}=52\)
\(\dfrac{7011}{25}:\left(x-42.6\right).15=13\)
\(\Rightarrow\dfrac{7011}{\dfrac{25}{\left(x-42,6\right)}}.0,15=13\)
\(\Rightarrow\dfrac{280,44}{\left(x-42,6\right)}.0,15=13\)
\(x-\left(280,44-42,6\right)\)
\(x=237.8+86,7\)
\(x=324,54\)
\(\)Vậy x=324,54
b.
\(7,2-\left(x+3,75:2,1\right):1,9=5,2\)
\(\Rightarrow7,2+\dfrac{-\left(x-\dfrac{3,75}{2,1}\right)}{1,9}=5,2\)
\(7,2+\dfrac{-\left(x-1,8\right)}{1,9}=5,2\)
a, x* 7,25 = 72,50
x = 72,50 : 7,25
x = 10
b, 470,04 : x = 24
x = 470,04 : 24
x = 19,585
c, 32,68 *x = 99,3472
x = 99,3472 : 32,68
x = 3,04
d, 625,17 : x = 6,2517
x = 625,17 : 6,2517
x = 100
\(a,\frac{7011}{25}:\left(x-42,6\right)=117,14-47,03\)
\(=\frac{7011}{25}:\left(x-42,6\right)=70,11\)
\(\Rightarrow\left(x-42,6\right)=\frac{7011}{25}:70,11\)
\(\Rightarrow x=4+42,6\)
\(\Rightarrow x=46,6\)
a) 7,25×6,93+7,25×2,07+7,25×1
=7,25×(6,93+2,07+1)
=7,25×10
=72,5
b) 24,8:0,5+24,8×8
=24,8×2+24,8×8
=24,8×(2+8)
=24,8×10
=248
Áp dụng tính chất của dãy tỷ số bằng nhau
\(\frac{3x-1}{40-5x}=\frac{25-3x}{4x-34}=\frac{\left(3x-1\right)+\left(25x-3x\right)}{\left(40-5x\right)+\left(5x-34\right)}=4\)
\(\Rightarrow\frac{3x-1}{40-5x}=4\)
\(\Rightarrow3x-1=3\left(40-5x\right)\)
\(\Rightarrow3x-1=160-20x\)
\(\Rightarrow23x=161\)
\(\Rightarrow x=161:23\)
\(\Rightarrow x=7\)
a) 25% x X = 39.32
X = 39.32 : 25% = 9.83
b) X : 40% = 14
X = 14 x 40% = 5.6