(x+3)(x-1)(x+1)(x-3)+15
Đặt A=(x+3)(x-1)(x+1)(x-3)+15
=(x+3)(x-3)(x-1)(x+1)+15
=(x2-9)(x2-1)+15
Đặt a=x2-9 \(\Rightarrow\) x2-1=a+8
Khi đó, ta có: A=a(a+8)+15
=a2+8a+15
=a2+3a+5a+15
=a(a+3)+5(a+3)
=(a+3)(a+5)
Thay a=x2-9 vào A, ta có:
A=(x2-9+3)(x2-9+5)
=(x2-6)(x2-4)
=(x-\(\sqrt{6}\))(x+\(\sqrt{6}\))(x-2)(x+2)
Phân tích đa thức thành nhân tử:
\(\left(x+y+z\right)^3-x^3-y^3-z^3\)
Tìm x biết :
a) \(\left(x-2\right)^3+6\left(x+1\right)^2-x^3+12=0\)
b) \(\left(x-5\right)\left(x+5\right)-\left(x+3\right)^3+3\left(x-2\right)^2=\left(x+1\right)^2-\left(x+4\right)\left(x-4\right)+3x^2\)
c) \(\left(2x+3\right)^2+\left(x-1\right)\left(x+1\right)=5\left(x+2\right)^2-\left(x-5\right)\left(x+1\right)+\left(x+4\right)^2\)
d) \(\left(1-3x\right)^2-\left(x-2\right)\left(9x+1\right)=\left(3x-4\right)\left(3x+4\right)-9\left(x+3\right)^2\)
Phân tích đa thức thành nhân tử
\(x^2\left(x^2-6\right)-x^2+9\)
PHƯƠNG PHÁP THÊM BỚT HẠNH TỬ VÀ PHƯƠNG PHÁP ĐỔI BIẾN :
a) \(4x^4+1\)
b) \(x^8+4\)
c) \(x^4+x^2+1\)
d) \(x^7+x^5+1\)
e) \(x^7+x^5-1\)
f) \(\left(x+2\right)\left(x+4\right)\left(x+6\right)\left(x+8\right)+16\)
g) \(\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24\)
h) \(\left(x-1\right)\left(x-3\right)\left(x-5\right)\left(x-7\right)-20\)
i) \(\left(x-1\right)\left(x+2\right)\left(x+3\right)\left(x+6\right)-28\)
1. \(\frac{1}{2}x^2-\left(\frac{1}{2}x-4\right)\frac{1}{2}x=-14\)
2. \(3\left(1-4x\right)\left(x-1\right)+4\left(3x-2\right)\left(x+3\right)=-27\)
3. \(6x\left(5x+3\right)+3x\left(1-10x\right)=7\)
4. \(\left(3x-3\right)\left(5-21x\right)+\left(7x+4\right)\left(9x-5\right)=44\)
5. \(\left(-2+x^3\right)\left(-2+x^2\right)\left(-2+x^2\right)=1\)
Thực hiện phép tính:
a) \(2x.\left(2x^2+3x-1\right)\)
b) \(\left(x+5\right).\left(2x-3\right)\)
c) \(\left(x+1\right)^2-x\left(2+3x\right)\)
d) \(\left(2x^3+x^2-8x+3\right):\left(2x-3\right)\)
Phân tích đa thức thành nhân tử
a) \(\left(x^2+x\right)^2+3\left(x^2+x\right)+2\)
b) \(x\left(x+1\right)\left(x+2\right)\left(x+3\right)+1\)
c) \(\left(x^2+x+1\right)\left(x^2+3x+1\right)+x^2\)
d) \(\left(1+x^2\right)^2-4x\left(1-x^2\right)\)
e) \(\left(x^2-8\right)^2+36\)
f) \(81x^4+4\)
Rút gọn biểu thức sau:
a, \(\left(x-2\right)\left(x^2+2x+4\right)-\left(x+1\right)^2+3\left(x-1\right)\left(x+1\right)\)
b, \(\left(x^4-5x^2+25\right)\left(x^2+5\right)-\left(2+x^2\right)^2+3\left(1+x^2\right)^2\)
Tính
\(A=\dfrac{1}{x\left(x+1\right)}+\dfrac{1}{\left(x+1\right)\left(x+2\right)}+\dfrac{1}{\left(x+2\right)\left(x+3\right)}+...+\dfrac{1}{\left(x+9\right)\left(x+10\right)}\)
