a) 14𝑥3𝑦∶10𝑥2
b) (𝑥3−27)∶(3−𝑥)
c) 8𝑥3𝑦3𝑧∶6𝑥𝑦3
d) (𝑥2−9𝑦2+4𝑥+4)∶(𝑥+3𝑦+2)
a) 14𝑥3𝑦∶10𝑥2
b) (𝑥3−27)∶(3−𝑥)
c) 8𝑥3𝑦3𝑧∶6𝑥𝑦3
d) (𝑥2−9𝑦2+4𝑥+4)∶(𝑥+3𝑦+2)
6) Làm tính chia
a) 14𝑥3𝑦∶10𝑥2
b) (𝑥3−27)∶(3−𝑥)
c) 8𝑥3𝑦3𝑧∶6𝑥𝑦3
d) (𝑥2−9𝑦2+4𝑥+4)∶(𝑥+3𝑦+2)
a) \(14x^3y:10x^2=\dfrac{7}{5}xy\)
b) \(\left(x^3-27\right):\left(3-x\right)\)
\(=\left(x-3\right)\left(x^2+3x+9\right):\left(3-x\right)\)
\(=-\left(3-x\right)\left(x^2+3x+9\right):\left(3-x\right)\)
\(=-\left(x^2+3x+9\right)\)
\(=-x^2-3x-9\)
c) \(8x^3y^3z:6xy^3=\dfrac{4}{3}x^2z\)
d) \(\left(x^2-9y^2+4x+4\right):\left(x^2+3y+2\right)\)
\(=\left[\left(x+2\right)^2-\left(3y\right)^2\right]:\left(x^2+3y+2\right)\)
\(=\left(x+3y+2\right)\left(x-3y+2\right):\left(x^2+3y+2\right)\)
\(=x-3y+2\)
6) Làm tính chia
a) 14𝑥3𝑦∶10𝑥2
b) (𝑥3−27)∶(3−𝑥)
c) 8𝑥3𝑦3𝑧∶6𝑥𝑦3
d) (𝑥2−9𝑦2+4𝑥+4)∶(𝑥+3𝑦+2)
6) Làm tính chia
a) 14𝑥3𝑦∶10𝑥2
b) (𝑥3−27)∶(3−𝑥)
c) 8𝑥3𝑦3𝑧∶6𝑥𝑦3
d) (𝑥2−9𝑦2+4𝑥+4)∶(𝑥+3𝑦+2)
Tìm x , biết rằng
a) 𝑥3 - 64𝑥 = 0
b) 𝑥3 - 4𝑥2 = -4𝑥
c)𝑥2 - 16 - (𝑥 - 4) = 0
d)(2𝑥 + 1)2 = (3 + 𝑥)
e)𝑥3 - 6𝑥2 + 12𝑥 - 8 = 0
f)𝑥3 - 7𝑥 - 6 = 0
a) x³ - 64x = 0
x(x² - 64) = 0
x(x - 8)(x + 8) = 0
x = 0 hoặc x - 8 = 0 hoặc x + 8 = 0
*) x - 8 = 0
x = 8
*) x + 8 = 0
x = -8
Vậy x = -8; x = 0; x = 8
b) x³ - 4x² = -4x
x³ - 4x² + 4x = 0
x(x² - 4x + 4) = 0
x(x - 2)² = 0
x = 0 hoặc (x - 2)² = 0
*) (x - 2)² = 0
x - 2 = 0
x = 2
Vậy x = 0; x = 2
c) x² - 16 - (x - 4) = 0
(x - 4)(x + 4) - (x - 4) = 0
(x - 4)(x + 4 - 1) = 0
(x - 4)(x + 3) = 0
x - 4 = 0 hoặc x + 3 = 0
*) x - 4 = 0
x = 4
*) x + 3 = 0
x = -3
Vậy x = -3; x = 4
d) (2x + 1)² = (3 + x)²
(2x + 1)² - (3 + x)² = 0
(2x + 1 - 3 - x)(2x + 1 + 3 + x) = 0
(x - 2)(3x + 4) = 0
x - 2 = 0 hoặc 3x + 4 = 0
*) x - 2 = 0
x = 2
*) 3x + 4 = 0
3x = -4
x = -4/3
Vậy x = -4/3; x = 2
e) x³ - 6x² + 12x - 8 = 0
(x - 2)³ = 0
x - 2 = 0
x = 2
f) x³ - 7x - 6 = 0
x³ + 2x² - 2x² - 4x - 3x - 6 = 0
(x³ + 2x²) - (2x² + 4x) - (3x + 6) = 0
x²(x + 2) - 2x(x + 2) - 3(x + 2) = 0
(x + 2)(x² - 2x - 3) = 0
(x + 2)(x² + x - 3x - 3) = 0
(x + 2)[(x² + x) - (3x + 3)] = 0
(x + 2)[x(x + 1) - 3(x + 1)] = 0
(x + 2)(x + 1)(x - 3) = 0
x + 2 = 0 hoặc x + 1 = 0 hoặc x - 3 = 0
*) x + 2 = 0
x = -2
*) x + 1 = 0
x = -1
*) x - 3 = 0
x = 3
Vậy x = -1; x = -1; x = 3
a,x\(^3\)-64=0
x\(^3\) =64
=>x=3
b,x\(^3\)-4x\(^2\)=-4x
x\(^3\)-4x\(^2\)+4x=0
x(x\(^2\)-4x+4)=0
x(x-2)\(^2\)=)
TH1:x=0
TH2:x-2=0
=>x=2
c,x\(^2\)-16-(x-4)=0
(x+4)(x-4)-(x-4)=0
(x-4)(x+4-1)=0
(x-4)(x+3)=0
TH1:x-4=0
=>x=4
TH2:x+3=0
=>x=-3
d,(2x+1).2=3+x
4x+2-3-x=0
3x-1=0
x=\(\dfrac{1}{3}\)
e,x\(^3\)-6x\(^2\)+12x-8=0
(x-2)\(^3\)=0
=>x-2=0
=>x=2
f,x\(^3\)-7x+6=0
x\(^3\)-x-6x+6=0
x(x\(^2\)-1)-6(x-1)=0
x(x+1)(x-1)-6(x-1)=0
(x-1)(x\(^2\)+x-6)=0
TH1:x-1=0
=>x=1
TH2:x\(^2\)+x-6=0
x\(^2\)+3x-2x-6=0
x(x+3)-2(x+3)=0
(x+3)(x-2)=0
=>x+3=0 =>x-2=0
+>x=-3 =>x=2
d,(2x+1)\(^2\)=(3+x)\(^2\)
4x\(^2\)+4x+1-9-6x-x\(^2\)=0
3x\(^2\)-2x-8=0
3x\(^2\)-6x+4x-8=0
3x(x-2)+4(x-2)=0
(3x+4)(x-2)=0
TH1:3x+4=0 TH2:x-2=0
=>x=\(\dfrac{-4}{3}\) =>x=2
e) 𝑥3−3𝑥2−4𝑥+12f) 𝑥3+27+(𝑥+3)(𝑥−9)
e) 𝑥3−3𝑥2−4𝑥+12f) 𝑥3+27+(𝑥+3)(𝑥−9)
e) x3-3x2-4x+12
= x2(x-3)-4(x-3)
= (x2-4)(x-3)
1) Làm tính nhân
a) 𝑥.(𝑥2–5)
b) 3𝑥𝑦(𝑥2−2𝑥2𝑦+3)
c) (2𝑥−6)(3𝑥+6)
d) (𝑥+3𝑦)(𝑥2−𝑥𝑦)
2)Tính (áp dụng Hằng đẳng thức)
a) (2𝑥+5)(2𝑥−5)
b) (𝑥−3)^2
c) (4+3𝑥)^2
d) (𝑥−2𝑦)^3
e) (5𝑥+3𝑦)^3
f) (5−𝑥)(25+5𝑥+𝑥^2)
g) (2𝑦+𝑥)(4𝑦^2−2𝑥𝑦+𝑥^2)
3)Phân tích các đa thức sau thành nhân tử
a) 𝑥^2+2𝑥
b) 𝑥^2−6𝑥+9
c) 5(𝑥–𝑦)–𝑦(𝑦–𝑥)
d) 2𝑥−𝑦^2+2𝑥𝑦−𝑦
a) 6𝑥^3𝑦^4+12𝑥^2𝑦^3−18𝑥^3𝑦^2
\(1,\\ a,=x^3-5x\\ b,=3x^3y-6x^3y^2+9xy\\ c,=6x^2-6x-36\\ d,=x^3+2x^2y-3xy^2\\ 2,\\ a,=4x^2-25\\ b,=x^2-6x+9\\ c,=9x^2+24x+16\\ d,=x^3-6x^2y+12xy^2-8y^3\\ e,=125x^3+225x^2y+135xy^2+27y^3\\ f,=125-x^3\)
\(g,=8y^3+x^3\\ 3,\\ a,=x\left(x+2\right)\\ b,=\left(x-3\right)^2\\ c,=\left(x-y\right)\left(y+5\right)\\ d,=2x\left(y+1\right)-y\left(y+1\right)=\left(2x-y\right)\left(y+1\right)\\ e,=6x^2y^2\left(xy^2+2y-3x\right)\)
Bài 8: Tìm giá trị nhỏ nhất của
A=√𝑥2 −4𝑥+25 ,
C=3+√𝑥 √𝑥+1
B=√𝑥2 −6𝑥+30
D=√𝑥2 −4𝑥+7+√2
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