3^8x+4=81^x=3
Những câu hỏi liên quan
giai phuong trinh 3∛x-3 +4∛8x-24 -1/3∛27x-81 =-20
Giải phương trình :
3\(\sqrt[3]{x-3}+4\sqrt[3]{8x-24}-\frac{1}{3}\sqrt[3]{27x-81}=-20\)
\(3\sqrt[3]{x-3}+4\sqrt[3]{8x-24}-\frac{1}{3}\sqrt[3]{27x-81}=3\sqrt[3]{x-3}+4\sqrt[3]{8\left(x-3\right)}-\frac{1}{3}\sqrt[3]{27\left(x-3\right)}=3\sqrt[3]{x-3}+4.2.\sqrt[3]{x-3}-\frac{1}{3}.3.\sqrt[3]{x-3}=3\sqrt[3]{x-3}+8\sqrt[3]{x-3}-\sqrt[3]{x-3}=10.\sqrt[3]{x-3}=-20\Leftrightarrow\sqrt[3]{x-3}=-2\Leftrightarrow x-3=-8\Leftrightarrow x=-5\)
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PHân tích đa thức thành nhân tử
A, x^3 - 4x^2 - 8x + 8
b, 6x^3 - x^2 - 486x + 81
c, x^(x^2 + 4) - x^2 + 4
d, x^4 - x^2 +4x - 1
e, x^(x + 4 ) - ( x + 4)^2 - ( x^2 - 1)
\(x^3-4x^2-8x+8\)
\(=x^3+2x^2-6x^2-12x+4x+8\)
\(=x^2\left(x+2\right)-6x\left(x+2\right)+4\left(x+2\right)\)
\(=\left(x+2\right)\left(x^2-6x+4\right)\)
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BT6:
A) (5x+1)^2=16/25
B) ( x - 1/3)^3=(2/3)^6
C)(8x - 1)^4=(2x+7)^4
D) (x -1)^5 =(2x-3)^5
E) ( x +1 )^8=(x+1)^10
G) (21-3)^4+(x+5)^6=0
H) 3x -4 = 81^3
a) (5x+1) ^ 2 = 4^2 : 5^ 2
( 5x+1) ^2 = (4:5) ^2
=> (5x+1) = ( 4 : 5) = 0.8
5x = 0.8 - 1
x = 0.7 : 5
x = 0,14
Tìm x
(15x-5) (4x-1) + (3x-7) (1-16x) =81
(2x+4) (x-4) +(x-5) (x-2) =3x+5 (x-4)
(8x-3) (3x+2) - (4x+7) (x+4) = (x+1) (5x-1)
Đề bài: Phân tích đa thức thành nhân tử:
a) x^ 4- 4x^3+ 8x + 3.
b) x^2 (y^2 - 4)^2 - 6x(y^2 - 4) + 9.
c) a^4 - 9a^3 + 81a^2 - 81
a) \(x^4-4x^{3^{ }}+8x+3\)
\(=\left(x^4+x^3\right)-\left(5x^3+5x^2\right)+\left(5x^2+5x\right)+\left(3x+3\right)\)
\(=x^{3^{ }}\left(x+1\right)-5x^{2^{ }}\left(x+1\right)+5x\left(x+1\right)+3\left(x+1\right)\)
\(=\left(x+1\right)\left(x^3-5x^2+5x+3\right)\)
\(=\left(x+1\right)\left[\left(x^3-3x^2\right)-\left(2x^2-6x\right)-\left(x-3\right)\right]\)
\(=\left(x+1\right)\left[x^2\left(x-3\right)-2x\left(x-3\right)-\left(x-3\right)\right]\)
\(=\left(x+1\right)\left(x-3\right)\left(x^2-2x-1\right)\)
\(=\left(x+1\right)\left(x-3\right)\left[\left(x-1\right)^2-2\right]\)
\(=\left(x+1\right)\left(x-3\right)\left(x-1-\sqrt{2}\right)\left(x-1+\sqrt{2}\right)\)
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b, \(x^2\left(y^2-4\right)^2-6x\left(y^2-4\right)+9\)
\(=\left[x\left(y^2-4\right)-3\right]^2\)
\(=\left(xy^2-4x-3\right)^2\)
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3. Tìm nghiệm của các đa thức sau:
a) x + 7; b) \(\dfrac{1}{2}\)x - 4; c) - 8x + 20; d) x2 -100;
e) 4x2 -81; f) x2 - 7; g) x2 - 9x; h) x3 + 3x.
b: 1/2x-4=0
=>1/2x=4
hay x=8
a: x+7=0
=>x=-7
e: 4x2-81=0
=>(2x-9)(2x+9)=0
=>x=9/2 hoặc x=-9/2
g: x2-9x=0
=>x(x-9)=0
=>x=0 hoặc x=9
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a)\(x+7=0=>x=-7\)
b)\(\dfrac{1}{2}x-4=0=>\dfrac{1}{2}x=4=>x=8\)
c)\(-8x+20=0=>-8x=-20=>x=\dfrac{5}{2}\)
d)\(x^2-100=0=>x^2=100=>\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)
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e)\(4x^2-81=0=>4x^2=81=>x^2=\dfrac{81}{4}=>\left[{}\begin{matrix}x=\dfrac{9}{2}\\x=-\dfrac{9}{2}\end{matrix}\right.\)
f)\(x^2-7=0=>x^2=7=>x=\sqrt{7}\)
g)\(x^2-9x=0=>x\left(x-9\right)=0=>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)
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Xem thêm câu trả lời
3. Tìm nghiệm của các đa thức sau:
a) x + 7; b) \(\dfrac{1}{2}\)x - 4; c) - 8x + 20; d) x2 -100;
e) 4x2 -81; f) x2 - 7; g) x2 - 9x; h) x3 + 3x.
a: x+7=0
nên x=-7
b: x-4=0
nên x=4
c: -8x+20=0
=>-8x=-20
hay x=5/2
d: x2-100=0
=>(x-10)(x+10)=0
=>x=10 hoặc x=-10
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a) x +7 =0
=>x = -7
b) x - 4 =0=>x = 4
c) -8x + 20 = 0 =>-8x =-20 =>\(x=-\dfrac{20}{-8}=\dfrac{5}{2}\)
d)\(x^2-100=0=>x^2=100>\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)
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e)\(4x^2-81=0=>4x^2=81=>x^2=\dfrac{81}{4}=>\left[{}\begin{matrix}x=\dfrac{9}{2}\\x=-\dfrac{9}{2}\end{matrix}\right.\)
f)\(x^2-7=0=>x^2=7=>x=\sqrt{7}\)
g)\(x^2-9x=0=>x\left(x-9\right)=0=>\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)
H)\(x^3+3x=0=>x\left(x^2 +3\right)=0=>\left[{}\begin{matrix}x=0\\x^2=-3\left(vl\right)\end{matrix}\right.\)
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Tìm x biết
(-3/4)^3x -1= 256/81
(5x+1) ^2 =36/49
(X-2/9)^3= (2/6)^6
(8x -1)^2n+1 = 5^2n +1