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a: =>\(x^2\cdot2\sqrt{2}+x\left(2+2\sqrt{2}\right)+4=0\)
\(\text{Δ}=\left(2\sqrt{2}+2\right)^2-4\cdot2\sqrt{2}\cdot4=12-24\sqrt{2}< 0\)
=>PTVN
b:
\(\Leftrightarrow2x^2+2x+\sqrt{3}-x^2+2\sqrt{3}x+\sqrt{3}=0\)
=>\(x^2+x\left(2\sqrt{3}+2\right)+2\sqrt{3}=0\)
\(\text{Δ}=\left(2\sqrt{3}+2\right)^2-4\cdot2\sqrt{3}=16>0\)
PT có hai nghiệm là;
\(\left\{{}\begin{matrix}x_1=\dfrac{-2\sqrt{3}-2-4}{2}=-\sqrt{3}-3\\x=\dfrac{-2\sqrt{3}-2+4}{2}=-\sqrt{3}+1\end{matrix}\right.\)
1.
$(x-2)(x-5)=(x-3)(x-4)$
$\Leftrightarrow x^2-7x+10=x^2-7x+12$
$\Leftrightarrow 10=12$ (vô lý)
Vậy pt vô nghiệm.
2.
$(x-7)(x+7)+x^2-2=2(x^2+5)$
$\Leftrightarrow x^2-49+x^2-2=2x^2+10$
$\Leftrightarrow 2x^2-51=2x^2+10$
$\Leftrightarrow -51=10$ (vô lý)
Vậy pt vô nghiệm.
3.
$(x-1)^2+(x+3)^2=2(x-2)(x+2)$
$\Leftrightarrow (x^2-2x+1)+(x^2+6x+9)=2(x^2-4)$
$\Leftrightarrow 2x^2+4x+10=2x^2-8$
$\Leftrightarrow 4x+10=-8$
$\Leftrightarrow 4x=-18$
$\Leftrightarrow x=-4,5$
4.
$(x+1)^2=(x+3)(x-2)$
$\Leftrightarrow x^2+2x+1=x^2+x-6$
$\Leftrightarrow x=-7$
a: =>9x^2+12x+4-9x^2+12x-4=5x+38
=>24x=5x+38
=>19x=38
=>x=2
e: =>x^3+1-2x=x^3-x
=>-2x+1=-x
=>-x=-1
=>x=1
f: =>x^3-6x^2+12x-8+9x^2-1=x^3+3x^2+3x+1
=>12x-9=3x+1
=>9x=10
=>x=10/9
b: \(\Leftrightarrow3x^2-12x+12+9x-9=3x^2+3x-9\)
=>-3x+3=3x-9
=>-6x=-12
=>x=2
a: =>x-2/5=3/4:1/3=3/4*3=9/4
=>x=9/4+2/5=45/20+8/20=53/20
b: =>x-2/3=7/3:4/5=7/3*5/4=35/12
=>x=35/12+2/3=43/12
c: 1/3(x-2/5)=4/5
=>x-2/5=4/5*3=12/5
=>x=12/5+2/5=14/5
d: =>2/3x-1/3-1/4x+1/10=7/3
=>5/12x-7/30=7/3
=>5/12x=7/3+7/30=77/30
=>x=77/30:5/12=154/25
e: \(\Leftrightarrow x\cdot\dfrac{3}{7}-\dfrac{2}{7}+\dfrac{1}{2}-\dfrac{5}{4}x+\dfrac{5}{2}=0\)
=>\(x\cdot\dfrac{-23}{28}=\dfrac{2}{7}-3=\dfrac{-19}{7}\)
=>x=19/7:23/28=76/23
f: =>1/2x-3/2+1/3x-4/3+1/4x-5/4=1/5
=>13/12x=1/5+3/2+4/3+5/4=257/60
=>x=257/65
i: =>x^2-2/5x-x^2-2x+11/4=4/3
=>-12/5x=4/3-11/4=-17/12
=>x=17/12:12/5=85/144
\(a,\left(2x-3\right)^3-\left(x-1\right)^3-2\left(x-2\right)\left(x+2\right)\)
\(=8x^3+36x^2+27x+27-\left(x^3-3x^2+3x-1\right)-2\left(x^2-4\right)\)
\(=8x^3+36x^2+27x+27-x^3+3x^2-3x+1-2x^2+8\)
\(=7x^3+37x^2+24x+36\)
\(b,\left(x-3\right)^2-2\left(x+2\right)^3-4\left(x+3\right)\left(x-3\right)\)
\(=x^2-6x+9-2\left(x^3+6x^2+12x+8\right)-4\left(x^2-9\right)\)
\(=x^2-6x+9-2x^3-12x^2-24x-16-4x^2+36\)
\(=-15x^2-30x-2x^3+45\)
\(c,\left(2x-5\right)^3-4\left(x-2\right)\left(x+2\right)-2\left(x+1\right)^3\)
\(=8x^3-10x^2+50x-25-4\left(x^2-4\right)-2\left(x^3+3x^2+3x+1\right)\)
\(=8x^3-10x^2+50x-25-4x^2+16-2x^3-6x^2-6x-2\)
\(=6x^3-20x^2+44x-11\)
\(A=\dfrac{\left(2-\sqrt[3]{x}\right)\left(4+2\sqrt[3]{x}+\sqrt[3]{x^2}\right)}{2+\sqrt[3]{x}}:\dfrac{4+2\sqrt[3]{x}+\sqrt[3]{x^2}}{2+\sqrt[3]{x}}+\dfrac{\sqrt[3]{x^2}-2\sqrt[3]{x}+2\sqrt[3]{x}}{\sqrt[3]{x}-2}.\dfrac{\left(\sqrt[3]{x}-2\right)\left(\sqrt[3]{x}+2\right)}{\sqrt[3]{x}\left(\sqrt[3]{x}+2\right)}\)
\(=\dfrac{\left(2-\sqrt[3]{x}\right)\left(4+2\sqrt[3]{x}+\sqrt[3]{x^2}\right)}{2+\sqrt[3]{x}}.\dfrac{2+\sqrt[3]{x}}{4+2\sqrt[3]{x}+\sqrt[3]{x^2}}+\dfrac{\sqrt[3]{x}.\sqrt[3]{x}}{\sqrt[3]{x}-2}.\dfrac{\left(\sqrt[3]{x}-2\right)\left(\sqrt[3]{x}+2\right)}{\sqrt[3]{x}\left(\sqrt[3]{x}+2\right)}\)
\(=2-\sqrt[3]{x}+\sqrt[3]{x}=2\)
X^3 - 2^3 = 2^5 - ( 3^16 : 3^14 + 2^8 : 2^6 )
X^3 - 2^3 = 2^5 - ( 3^2 + 2^2 )
X^3 - 2^3 = 2^5 - 13
X^3 - 2^3 = 19
X^3 = 19 + 2^3
X^3 = 27
nên X = 3 vì 3^3 = 27
nha bạn