Toán tìm x biết a)x+70=2^3.3^2 b)2-|x+1|=0 c)15-(2x-3)^3=-12 22/11/2021 By Lyla tìm x biết a)x+70=2^3.3^2 b)2-|x+1|=0 c)15-(2x-3)^3=-12
Đáp án: Giải thích các bước giải: a) x+70=2^3.3^2 x+70=8.9 x+70=72 x=2 b)2-|x+1|=0 |x+1|=2 TH1:x=2-1 x=1 TH2:x+1=-2 x=(-2)-1 x=-3 c)15-(2x-3)^3=-12 (2x-3)^3=15-(-12) (2x-3)^3=27 vì:3^3=27 =>2x-3=3 2x=6 x=6:2=3 Trả lời
`a)x+70=2^3 . 3^2` `⇔x+70=8.9` `⇔x+70=72` `⇔x=2` `b)2-|x+1|=0` `⇔|x+1|=2` `⇔x+1=±2` `th1: x+1=2` `⇒x=1` `Th2 x+1=-2` `⇒x=-3` `c)15-(2x-3)^3=-12` `⇔27=(2x-3)^3` `⇔3^3=(2x-3)^3` `⇔2x-3=3` `⇔2x=6` `⇔x=3` Trả lời
Đáp án:
Giải thích các bước giải:
a) x+70=2^3.3^2
x+70=8.9
x+70=72
x=2
b)2-|x+1|=0
|x+1|=2
TH1:x=2-1
x=1
TH2:x+1=-2
x=(-2)-1
x=-3
c)15-(2x-3)^3=-12
(2x-3)^3=15-(-12)
(2x-3)^3=27
vì:3^3=27
=>2x-3=3
2x=6
x=6:2=3
`a)x+70=2^3 . 3^2`
`⇔x+70=8.9`
`⇔x+70=72`
`⇔x=2`
`b)2-|x+1|=0`
`⇔|x+1|=2`
`⇔x+1=±2`
`th1: x+1=2`
`⇒x=1`
`Th2 x+1=-2`
`⇒x=-3`
`c)15-(2x-3)^3=-12`
`⇔27=(2x-3)^3`
`⇔3^3=(2x-3)^3`
`⇔2x-3=3`
`⇔2x=6`
`⇔x=3`