a. 2-10x > 14 – 2x
b. $\frac{x+1}{3}$ $\leq$ $\frac{1-3x}{5}$
c. $\frac{x-2}{6}$ $\geq$ $\frac{x+3}{5}$
a. 2-10x > 14 – 2x b. $\frac{x+1}{3}$ $\leq$ $\frac{1-3x}{5}$ c. $\frac{x-2}{6}$ $\geq$ $\frac{x+3}{5}$
By Maya
By Maya
a. 2-10x > 14 – 2x
b. $\frac{x+1}{3}$ $\leq$ $\frac{1-3x}{5}$
c. $\frac{x-2}{6}$ $\geq$ $\frac{x+3}{5}$
a) 2-10x > 14 – 2x
⇔ -10x+2x > -2+14 (chuyển vế đổi dấu)
⇔ -8x > 12
⇔ -8x . $\frac{-1}{8}$ < 12 . $\frac{-1}{8}$ ( nhân cả 2 vế cho $\frac{-1}{8}$ )
⇔ x < $\frac{-3}{2}$
Vậy S={x/x<$\frac{-3}{2}$ }
b) $\frac{x+1}{3}$ $\leq$ $\frac{1-3x}{5}$
⇔ $\frac{(x+1).5}{3.5}$ $\leq$ $\frac{(1-3x).3}{5.3}$
⇔ (x+1).5 $\leq$ (1-3x).3
⇔ 5x+5 $\leq$ 3-9x
⇔ 5x+9x $\leq$ -5+3
⇔ 14x $\leq$ -2
⇔ 14x.$\frac{1}{14}$ $\leq$ -2.$\frac{1}{14}$
⇔ x $\leq$ $\frac{-1}{7}$
Vậy S={x/x$\leq$ $\frac{-1}{7}$}
c) $\frac{x-2}{6}$ $\geq$ $\frac{x+3}{5}$
⇔ $\frac{(x-2).5}{6.5}$ $\geq$ $\frac{(x+3).6}{5.6}$
⇔ (x-2).5 $\geq$ (x+3).6
⇔ 5x-10 $\geq$ 6x+18
⇔ 5x -6x $\geq$ 10+18
⇔ -x $\geq$ 28
⇔ x $\leq$ -28 ( nhân cả 2 vế cho -1)
Vậy S={x/x $\leq$ -28}
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Đáp án:
`a,` `{x| x<-3/2}`
`b,` `{x| x` $\leq$ `-1/7“}`
`c,` `{x| x` $\leq$ `-28“}`
Giải thích các bước giải:
`a, 2-10x>14-2x`
`<=> -10x+2x>14-2`
`<=>-8x>12`
`<=>x<-3/2`
`KL:` `{x| x<-3/2}`
`b, (x+1)/3` $\leq$ `(1-3x)/5`
`<=> 5(x+1)` $\leq$ `3(1-3x)`
`<=>5x+5` $\leq$ `3-9x`
`<=> 5x+9x` $\leq$ `3-5`
`<=>14x` $\leq$ `-2`
`<=>x` $\leq$ `-1/7`
`KL:` `{x| x` $\leq$ `-1/7“}`
`c, (x-2)/6` $\geq$ `(x+3)/5`
`<=>5(x-2)` $\geq$ `6(x+3)`
`<=>5x-10`$\geq$ `6x+18`
`<=>5x-6x` $\geq$ `18+10`
`<=>-x` $\geq$ `28`
`<=>x` $\leq$ `-28`
`KL:` `{x| x` $\leq$ `-28“}`