tìm số tự nhiên x bết : a) 4x.(x-32)=0 b) (x-3)(x-8)=0 f) (2x-2).45=0 g) 32.(5x-8)=32
h) (x-4).(x-7)=0 i) 5x.(3x-15)=0 k) (2x-3)(x-2)=0
tìm số tự nhiên x bết : a) 4x.(x-32)=0 b) (x-3)(x-8)=0 f) (2x-2).45=0 g) 32.(5x-8)=32
h) (x-4).(x-7)=0 i) 5x.(3x-15)=0 k) (2x-3)(x-2)=0
Đáp án:
Giải thích các bước giải:
a)4x(x-32)=0
⇒4x=0 hay x-32=0
⇒x=0 hay x=32
vậy x=0 hay x=32
b)(x-3)(x-8)=0
⇒x-3 =0 hay x-8=0
⇒x=3 hay x=8
vậy x=3 hay x=8
f)(2x-2)45=0
⇒90x-90=0
⇒90x=90
⇒x=1
vậy x=1
g)32(5x-8)=32
⇒160x-256=32
⇒160x=32+256
⇒160x=288
⇒x=288/160
⇒x=1,8
vậy x=1,8
h)(x-4)(x-7)=0
⇒x-4=0 hay x-7=0
⇒x=4 hay x=7
vậy x=4 hay x=7
i)5x(3x-15)=0
⇒5x=0 hay 3x-15=0
⇒x=0 hay x=5
vậy x=0 hay x=5
k)(2x-3)(x-2)=0
⇒2x-3=0 hay x-2=0
⇒x=3/2 hay x=2
`a,4x(x-32)=0`
`⇔` \(\left[ \begin{array}{l}4x=0\\x-32=0\end{array} \right.\) `⇔` \(\left[ \begin{array}{l}x=0\\x=32\end{array} \right.\)
`b,(x-3)(x-8)=0`
`⇔` \(\left[ \begin{array}{l}x-3=0\\x-8=0\end{array} \right.\) `⇔` \(\left[ \begin{array}{l}x=3\\x=8\end{array} \right.\)
`f,(2x-2).45=0`
`⇔2x-2=0`
`⇔2(x-1)=0`
`⇔x-1=0`
`⇔x=1`
`g,32(5x-8)=32`
`⇒5x-8=1`
`⇔5x=9`
`⇔x=9/5`
`h,(x-4)(x-7)=0`
`⇔` \(\left[ \begin{array}{l}x-4=0\\x-7=0\end{array} \right.\) `⇔` \(\left[ \begin{array}{l}x=4\\x=7\end{array} \right.\)
`i,5x(3x-15)=0`
`⇔` \(\left[ \begin{array}{l}5x=0\\3x-15=0\end{array} \right.\) `⇔` \(\left[ \begin{array}{l}x=0\\x=5\end{array} \right.\)
`k,(2x-3)(x-2)=0`
`⇔` \(\left[ \begin{array}{l}2x-3=0\\x-2=0\end{array} \right.\) `⇔` \(\left[ \begin{array}{l}x=\dfrac{3}{2}\\x=2\end{array} \right.\)