2 of - to

3 on

4 on

5 with

6 of - with

7 with

 \(a)P=\left(\dfrac{x^2+2}{x^3-1}+\dfrac{x+1}{x^2+x+1}+\dfrac{1}{1-x}\right).\left(\dfrac{x^2}{x+1}+1\right).\left(x\ne1;x\ne-1\right).\\ P=\dfrac{x^2+2+x^2-1-x^2-x-1}{\left(x-1\right)\left(x^2+x+1\right)}.\dfrac{x^2+x+1}{x+1}.\\ P=\dfrac{x^2-x}{x-1}.\dfrac{1}{x+1}.\\ P=\dfrac{x\left(x-1\right)}{x-1}.\dfrac{1}{x+1}.\\ P=x.\dfrac{1}{x+1}.\\ P=\dfrac{x}{x+1}.\)

\(P=\dfrac{1}{4}.\Rightarrow\dfrac{x}{x+1}=\dfrac{1}{4}.\\ \Leftrightarrow4x-x-1=0.\\ \Leftrightarrow3x-1=0.\\ \Leftrightarrow x=\dfrac{1}{3}\left(TM\right).\)

\(a^4:a^4\)

\(=a^{4-4}\)

\(=a^0\)

\(=1\)

Ta có:

\(a^4:a^4\)\(=a^{4-4}=a^0=1\)

Câu 45:

ta có C2O4 2- -> 2CO2 + 2e -> n=2

Đ= M/n = 90/2=45

=> chọn B

LỚP 10 THÌ THUI RÙI

B

B