a: \(\left(x-1\right)^2+x\left(x+4\right)\)
\(=x^2-2x+1+x^2+4x\)
\(=2x^2+2x+1\)
b: \(\left(x-2\right)^2+\left(3x-2\right)\left(3x+2\right)\)
\(=x^2-4x+4+9x^2-4\)
\(=10x^2-4x\)
c: ĐKXĐ: \(x\notin\left\{-3;3\right\}\)
\(\dfrac{2x}{x+3}+\dfrac{5}{x-3}+\dfrac{-2x^2+2x-18}{x^2-9}\)
\(=\dfrac{2x}{x+3}+\dfrac{5}{x-3}+\dfrac{-2x^2+2x-18}{\left(x-3\right)\left(x+3\right)}\)
\(=\dfrac{2x\left(x-3\right)+5\left(x+3\right)-2x^2+2x-18}{\left(x+3\right)\left(x-3\right)}\)
\(=\dfrac{2x^2-6x+5x+15-2x^2+2x-18}{\left(x+3\right)\left(x-3\right)}\)
\(=\dfrac{x-3}{\left(x-3\right)\left(x+3\right)}=\dfrac{1}{x+3}\)
Đúng 1
Bình luận (0)
