[ 308 - ( x - 6 ) ] . 15 = 1545
138 - 5 ( x + 4 ) = 38
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a, 3/4 ÷ x/6 = 0,75
x/6 = 0,75 ÷ 0,75
x/6 = 1
=> x = 6
Vậy x = 6
b, 2,5 . 45/ x = 5/6
45/x = 5/6 ÷ 2,5
45/x = 1/3
=> x = 45 × 3
=> x = 135
Vậy x = 135
c, x/12 + 121,5 = 121,5
x/12 = 121,5 - 121,5
x/12 = 0
=> x = 0
Vậy x = 0
e, 6/8 = 15/x
3/4 = 15/x
=> x = 20
Vậy x = 20
Hiệu x – y | 432 | 308 | 602 | 2000 | 2345 |
Tỉ số x : y | 4:1 | 2:1 | 6:3 | 5:3 | 7:2 |
x | 576 | 616 | 1206 | 5000 | 3283 |
y | 144 | 308 | 603 | 3000 | 938 |
`5/9+(-4)/5<x/15<-4/9+3/5`
`-11/15 < x/15 <7/45`
`-33/45 <(3x)/45 <7/45`
`-33<3x<7`
`-11<x<7/3`
`=> x \in {-10;-9;....2}` (Nếu `x \in ZZ)`
`x \in {0;1;2}` (Nếu `x \in NN`).
\(ĐKXĐ:x\ne\pm5\)
\(\frac{3}{4\left(x-5\right)}+\frac{15}{50-2x^2}=\frac{-7}{6\left(x+5\right)}\)
\(\Rightarrow\frac{3\left(x+5\right)}{4\left(x-5\right)\left(x+5\right)}+\frac{30}{4\left(25-x^2\right)}=\frac{-7\left(x-5\right)}{6\left(x+5\right)\left(x-5\right)}\)
\(\Rightarrow\frac{3x+15}{4\left(x-5\right)\left(x+5\right)}+\frac{-30}{4\left(x-5\right)\left(x+5\right)}=\frac{-7\left(x-5\right)}{6\left(x+5\right)\left(x-5\right)}\)
\(\Rightarrow\frac{3x+15-30}{4\left(x-5\right)\left(x+5\right)}=\frac{-7\left(x-5\right)}{6\left(x+5\right)\left(x-5\right)}\)
\(\Rightarrow\frac{3x-15}{4\left(x-5\right)\left(x+5\right)}=\frac{-7\left(x-5\right)}{6\left(x+5\right)\left(x-5\right)}\)
\(\Rightarrow\frac{3\left(x-5\right)}{4\left(x-5\right)\left(x+5\right)}=\frac{-7\left(x-5\right)}{6\left(x+5\right)\left(x-5\right)}\)
\(\Rightarrow\frac{3}{4\left(x+5\right)}=\frac{-7}{6\left(x+5\right)}\)
\(\Rightarrow18\left(x+5\right)=-28\left(x+5\right)\)
\(\Rightarrow18\left(x+5\right)+28\left(x+5\right)=0\)
\(\Rightarrow46\left(x+5\right)=0\Leftrightarrow x+5=0\Leftrightarrow x=-5\)(ktm)
Vậy pt vô nghiệm
`x xx 3/8=5/6+3/5`
`=> x xx 3/8 = 25/30 + 18/30`
`=> x xx 3/8 = 43/30`
`=> x=43/30:3/8`
`=>x=43/30xx8/3`
`=>x=172/45`
Theo bài ra ta có:
\(\left(x-5\right)4=\left(x-5\right)6\)
\(\Rightarrow4x-20=6x-30\)
\(\Rightarrow4x-6x=-30+20\)
\(\Rightarrow-2x=-10\Rightarrow x=\left(-10\right)\div\left(-2\right)=5\)
Vậy giá trị của x là 5.
[ 308 - ( x - 6 ) ] . 15 = 1545
<=> 308 - x + 6 = 103
<=> 308 - x = 103 - 6 = 97
<=> x = 308 - 97 = 211
138 - 5 ( x + 4 ) = 38
<=> 138 - 5x -20 =38
<=> 138 - 5x = 38 + 20 = 58
<=> 5x = 138 - 58 = 80
<=> x = 16
308 - ( x - 6 ) = 1545 : 15
308 - ( x - 6 ) = 103
x - 6 = 308 - 103
x - 6 = 205