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Bài 1:
y/0,25+y*11-y*5=1.8
y*4+y*11-y*5=1.8
y*(4+11-5)=1.8
10y=1.8
y=0.18
Bài 2:
0.32+56*0.95-31*12=0.32+53.2-372=-318.48
78/0.25*3+45*9=78*4*3+45*9=78.12+45.9=936-405=531
x : 0,25 + x : 0,5 + x + x : 0,01 = 321
\(x\times4+x\times2+x+x\times100=321\)
\(x\times\left(4+2+1+100\right)=321\)
\(x\times107=321\)
\(x=321:107\)
x = 3
X x 4 + X x 2 + X + X x 100 = 321
X x (4 + 2 + 1 + 100) = 321
X x 107 = 321
X = 321 : 107
X = 3
x : 0,25 + x : 0.5 + x + x : 0.01 = 321
x * 4 + x * 2 + x * 1 + x * 100 = 321
x * ( 4 + 2 + 1 + 100 ) = 321
x * 107 = 321
x = 321 : 107
x = 3
x : 0.25 + x : 0.5 + x + x :0.01 = 214
x : ( 0,25 + 0,5 + 0,01 ) = 214
x : 0, 31 = 214
x= 214 x 0,31
x =66,34
b) y + y : 0,5 + y : 0,25 + y : 0,125 = 15
yx1+yx2+yx4+yx8=15
yx(1+3+4+8)=15
yx15=15
y=15:15
y=1
- Ta có: \(\frac{3}{x}+\frac{y}{3}=\frac{5}{6}\)
\(\Leftrightarrow\frac{3}{x}=\frac{5}{6}-\frac{y}{3}\)
\(\Leftrightarrow\frac{3}{x}=\frac{5-2y}{6}\)
\(\Leftrightarrow x.\left(5-2y\right)=18=1.18=\left(-1\right).\left(-18\right)=2.9=\left(-2\right).\left(-9\right)=3.6=\left(-3\right).\left(-6\right)\)
- Vì \(5-2y\)là lẻ \(\Rightarrow\)\(5-2y\in\left\{-9,-3,-1,1,3,9,\right\}\)
- Ta có bảng giá trị:
\(5-2y\) | \(-9\) | \(-3\) | \(-1\) | \(1\) | \(3\) | \(9\) |
\(x\) | \(-2\) | \(-6\) | \(-18\) | \(18\) | \(6\) | \(2\) |
\(y\) | \(7\) | \(4\) | \(3\) | \(2\) | \(1\) | \(-2\) |
\(\left(TM\right)\) | \(\left(TM\right)\) | \(\left(TM\right)\) | \(\left(L\right)\) | \(\left(L\right)\) | \(\left(L\right)\) |
Vậy \(\left(x,y\right)\in\left\{\left(-2,7\right);\left(-6,4\right);\left(-18,3\right)\right\}\)
!@#$!@$! ^_^ Chúc bn hok tốt ^_^ @#$!#$!
Tìm y :
( y + 1/3 ) + ( y + 1/9 ) + ( y + 1/27 ) + ( y + 1/81 ) = 56/81
y + 1/3 + y + 1/9 + y + 1/27 + y + 1/81 = 56/81
y x 4 + ( 1/3 + 1/9 + 1/27 +1/81 ) = 56/81
y x 4 + ( 27/81 + 9/81 + 3/81 + 1/81 ) = 56/81
y x 4 + 40/81 = 56/81
y x 4 = 56/81 - 40/81
y x 4 = 16/81
y = 16/81 : 4
y = 4/81
y : 0,25 + y + y : 0,01 = 2016
y x 4 + y x 1 + y x 100 = 2016
y x ( 4 + 1 + 100 ) = 2016
y x 105 = 2016
y = 2016 : 105
y = 19,2
y*4+y+y*100=2016
y*(4+1+100)=2016
y*105=2016
y=2016:105
y=19,2