Toán Lớp 7: (x+0,1)³ +8=0
(x-2/5).(x+3/7)=0
2x² – 4/3x=0
3 mũ x-1 +5/3 .3x=162
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Toán Lớp 7: (x+0,1)³ +8=0
(x-2/5).(x+3/7)=0
2x² – 4/3x=0
3 mũ x-1 +5/3 .3x=162
Comments ( 2 )
(x+0,1)^3+8=0
(x+0,1)^3=0-8
(x+0,1)^3=-8
(x+0,1)^3=-2^3
=>x+0,1=-2
=>x=-2-0,1
=>x=-2,1
Vậy -2,1
(x-2/5).(x+3/7)=0
=>x-2/5=x+3/7
=>[(x-2/5=0),(x+3/7=0):}
=>[(x=0+2/5),(x=0-3/7):}
=>[(x=2/5),(x=-3/7):}
=>x in{2/5;-3/7}
Vậy x in{2/5;-3/7}
2x^2-4/3x=0
2x(x-2/3)=0
=>2x=x-2/3
=>[(2x=0),(x-2/3=0):}
=>[(x=0:2),(x=0+2/3):}
=>[(x=0),(x=2/3):}
=>x in{0;2/3}
Vậy x in{0;2/3}
3^(x-1)+5/3. 3^x=162
3^x:3+5/3. 3^x=162
3^x. 1/3+5/3. 3^x=162
3^x. (1/3+5/3)=162
3^x. 2=162
3^x=162:2
3^x=81
3^x=3^4
=>x=4
Vậy x=4
@Ki ng
a, (x + 0,1)^3 + 8 = 0
=> (x + 0,1)^3 = -8
=> (x + 0,1)^3 = (-2)^3
=> x + 0,1 = -2
=> x = -2 – 0,1
=> x = -2,1
Vậy x = -2,1
b, (x – 2/5).(x + 3/7) = 0
=> \(\left[ \begin{array}{l}x-\dfrac{2}{5}=0\\x+\dfrac{3}{7}=0\end{array} \right.\) => \(\left[ \begin{array}{l}x=\dfrac{2}{5}\\x=-\dfrac{3}{7}\end{array} \right.\)
Vậy x in {2/5; (-3)/7}
c, 2x^2 – 4/3x = 0
=> 2x(x – 2/3) = 0
=> \(\left[ \begin{array}{l}2x=0\\x-\dfrac{2}{3}=0\end{array} \right.\)
=> \(\left[ \begin{array}{l}x=0\\x=\dfrac{2}{3}\end{array} \right.\)
Vậy x in {0;2/3}
d, 3^(x-1) + 5/3. 3^x = 162
=> 3^x : 3 + 5/3. 3^x = 162
=> 3^x. 1/3 + 5/3. 3^x = 162
=> 3^x. (1/3 + 5/3) = 162
=> 3^x. 2 = 162
=> 3^x = 81
=> 3^x = 3^4
=> x = 4
Vậy x = 4