Toán Lớp 6: a) 2.x^3=-54
b)(2.x+3)^3=1
c)(2.x-1)^2=1
d)(2.x-1)^2=25
e) 4.(x+1)^2=36
f) 5.(x-3)^2=45
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Toán Lớp 6: a) 2.x^3=-54
b)(2.x+3)^3=1
c)(2.x-1)^2=1
d)(2.x-1)^2=25
e) 4.(x+1)^2=36
f) 5.(x-3)^2=45
giúp mình với nhanh lên nhé
Comments ( 2 )
$ a) 2 . x^3 = -54 $
$ x^3 = -54 : 2 = -27 ⇒ x = -3 $
$ b) (2x+3)^3=1 $
$ ⇒ 2x+3=1 $
$ 2x=1-3=-2 $
$ x=-2:2=-1 $
$ c) (2x-1)^2=1 $
$ ⇒ $ \(\left[ \begin{array}{l}2x-1=1⇒2x=2⇒x=1\\2x-1=-1⇒2x=0⇒x=0\end{array} \right.\)
$ d) ( 2x-1)^2=25 $
$ ⇒ $ \(\left[ \begin{array}{l}2x-1=5⇒2x=6⇒x=3\\2x-1=-5⇒2x=-4⇒x=-2\end{array} \right.\)
$ e) 4(x+1)^2=36 $
$ (x+1)^2 = 36:4=9 $
$ ⇒ $ \(\left[ \begin{array}{l}x+1=3⇒x=3-1=2\\x+1=-3⇒x=-3-1=-4\end{array} \right.\)
$ f) 5.(x-3)^2=45 $
$ (x-3)^2=45:5=9 $
$ ⇒ $ \(\left[ \begin{array}{l}x-3=3⇒x=3+3=6\\x-3=-3⇒x=-3+3=0\end{array} \right.\)
Giải đáp:+Lời giải và giải thích chi tiết:
a)2.x^3=-54
x^3=-54:2
x^3=-27
x^3=(-3)^3
=>x=-3
b)(2.x+3)^3=1
(2.x+3)^3=1^3
2.x+3=1
2.x=1-3
2.x=-2
x=2:2
x=-1
c)(2.x-1)^2=1
$\left[ \begin{array}{l}2x-1=1⇒2x=2⇒x=1\\2x-1=-1⇒2x=0⇒x=0\end{array} \right.$
d)(2x-1)^2=25
$\left[ \begin{array}{l}2x-1=5⇒2x=6⇒x=3\\2x-1=-5⇒2x=-4⇒x=-2\end{array} \right.$
e)4.(x+1)^2=36
(x+1)^2=36:4
(x+1)^2=9
$\left[ \begin{array}{l}x+1=3⇒x=3-1=2\\x+1=-3⇒x=-3-1=-4\end{array} \right.$
f) 5.(x-3)^2=45
(x-3)^2=45:5=9
$\left[ \begin{array}{l}x-3=3⇒x=3+3=6\\x-3=-3⇒x=-3+3=0\end{array} \right.$