a) \(\dfrac{1}{x^2+x}+\dfrac{1}{x^2+3x+2}+\dfrac{1}{x^2+5x+6}+\dfrac{1}{x^2+7x+12}\)
b) \(\dfrac{1}{x^2+3x+2}+\dfrac{1}{x^2+5x+6}+\dfrac{1}{x^2+7x+12}+\dfrac{1}{x^2+9x+20}\)
CMR \(\dfrac{1}{x}-\dfrac{1}{x+1}=\dfrac{1}{x\left(x+1\right)}\)
áp dụng kết quả bài toán trên, tính:
\(\dfrac{1}{^{^{ }}x^2+x}+\dfrac{1}{x^2+3\text{x}+2}+\dfrac{1}{x^2+6\text{x}+6}+\dfrac{1}{x^2+7\text{x}+12}+\dfrac{1}{x^2+9\text{x}+20}+\dfrac{1}{x+5}_{ }\)
1/1-x +1/1+x +2/1+x^2 +4/1+x^4 +8/1+x^8 +16/1+x^16 = 32/1-x^32 c/m
Rút gọn: A= 7(23+1)(26+1)(212+1)(224+1)
Bài 1: Rút gọn phân thức
a) \(\dfrac{36\left(x-2\right)^3}{32-16x}\)
b) \(\dfrac{x^2+2x+1}{x+1}\)
c) \(\dfrac{x^2-2x+1}{x^2-1}\)
d) \(\dfrac{3x^2-12x+12}{x^4-8x}\)
Chứng minh rằng:
1+a+a^2+a^3+...+a^62+a^63=(1+a)(1+a^2)(1+a^4)...(1+a^32)
Tính tổng sau : \(S=10+\dfrac{12}{1+2}+\dfrac{12}{1+2+3}+\dfrac{12}{1+2+3+4}+...+\dfrac{12}{1+2+...+2011}\)
Giải các phương trình sau :
1.\(\dfrac{14}{3x-12}-\dfrac{2+x}{x-4}=\dfrac{3}{8-2x}-\dfrac{5}{6}\)
2.\(\dfrac{12}{1-9x^2}=\dfrac{1-3x}{1+3x}-\dfrac{1+3x}{1-3x}\)
3.\(\dfrac{x+5}{x^2-5x}-\dfrac{x+25}{2x^2-50}=\dfrac{x-5}{2x^2+10x}\)
4.\(\dfrac{6x_{ }+1}{x^2-7x+10}+\dfrac{5}{x-2}=\dfrac{3}{x-5}\)
5.\(\dfrac{2}{x^2-4}-\dfrac{x-1}{x\left(x-2\right)}+\dfrac{x-4}{x\left(x+2\right)}=0\)
6.\(\dfrac{2}{x+2}-\dfrac{2x^2+16}{x^3+8}=\dfrac{5}{x^2-2x+4}\)
Dạng 1: Rút gọn biểu thức
1:3x(x-2)-5x(1-x)-8(x^2-3)
2:(4x-5)(2x+3)-4(x+2)(2x-1)+10x+7
3:(6x+1)^2+(6x-1)^2-2(1+6x)(6x-1)
4: (x^2-2x+2)(x^2-2)(x^2+2x+2)(x^2+2)
5: (x+1)^3+(x-1)^3+x^3-3x(x+1)(x-1)
6:3(2^2+1)(2^4+1)........(2^64+1)+1