Question

15 баллов.
сократите дробь.

Answer 1

$displaystyle frac{3x^{2}-11x-4}{12+x-x^{2}}= frac{3(x-4)(x+ frac{1}{3})}{(x+3)(x-4)}= frac{3x+1}{x+3}; \ \3x^{2}-11x-4=0 \ D=b^{2}-4ac=121+48=169 \ \ x_{1} = frac{-b+ sqrt{D} }{2a}=24:6=4 \ \ x_{2}= frac{-b- sqrt{D}}{2a}=-2:6=- frac{1}{3} \ \ -x^{2} +x+12=0 \ D=b^{2}-4ac=1+48=49 \ \ x_{1}= frac{-b+ sqrt{D} }{2a}=6:(-2)=-3 \ \ x_{2}= frac{-b- sqrt{D}}{2a}=-8:(-2) = 4$

$displaystyle frac{2-5x-2y+5xy}{10x^{3}-9x^{2}+2x}= frac{2(1-y)-5x(1-y)}{x(10 x^{2} -9x+2)}= frac{(2-5x)(1-y)}{10x(x-0,5)(x-0,4)}= \ \ =-frac{(5x-2)(1-y)}{x(2x-1)(5x-2)}=- frac{1-y}{x(2x-1)}; \ \10 x^{2} -9x+2=0 \ D= b^{2}-4ac=81-80=1 \ \ x_{1}= frac{-b+ sqrt{D} }{2a}=10:20=0,5 \ \x_{2}= frac{-b- sqrt{D}}{2a}=8:20=0,4$