√(5x²+10x+1)+1/5(5x²+10x+1)-1/5=71/5(5x²+10x+1)+√(5x²+10x+1)-36/5=0[√(5x²+10x+1)]^2+5√(5x²+10x+1)-36=0√(5x²+10x+1)=-9(舍）√(5x²+10x+1)=45x²+10x...