1/x(x+2)+1/(x+1)²=7/12

1/(x²+2x) + 1/(x²+2x+1)=7/12 x²+2x=a 1/a +1/(a+1)=7/12 12(a+1+a)=7a(a+1) 7a²-17a-12=0 D=289+336=625 a1=(17-25)/14=-4/7⇒x²+2x=-4/7 7x²+14x+4=0 D=196-112=84 x1=(-14-2√21)/14=-1-√21/7 x2=-1+√21/7 a2=(17+25)/14=8/7⇒x²+2x=8/7 7x²+14x-8=0 D=196+224=420 x3=(-14-2√105)/14=-1-√105/7 x4=-1+√105/7