\(2x\left(1-2x\right)+\left(x-1\right)^2=2x-4x^2+x^2-2x+1=-3x^2+1\)

\(A=\left(\dfrac{1}{x-9}-\dfrac{1}{x+6\sqrt{x}+9}\right).\dfrac{x+2\sqrt{x}}{x}\\ =\left(\dfrac{1}{\left(\sqrt{x}-3\right)\left(\sqrt{x}+3\right)}-\dfrac{1}{\left(\sqrt{x}+3\right)^2}\right).\dfrac{\sqrt{x}+2}{\sqrt{x}}\\ =\dfrac{\sqrt{x}+3-\sqrt{x}+3}{\left(\sqrt{x}+3\right)^2\left(\sqrt{x}-3\right)}.\dfrac{\sqrt{x}+2}{\sqrt{x}}\\ =\dfrac{6\left(\sqrt{x}+2\right)}{\sqrt{x}\left(\sqrt{x}+3\right)^2\left(\sqrt{x}-3\right)}\)

Bài 2.

Trung bình cộng hai số là: \(1516-173=1343\)

Tổng hai số là: \(1343\times2=2686\)

Số bé là: \(2686-1516=1170\)

Bài 1.

Hiệu hai chu vi là: \(4\times4=16\left(cm\right)\)

Chu vi hình vuông lớn là: \(\left(136+16\right):2=76\left(cm\right)\)

Chu vi hình vuông nhỏ là: \(76-16=60\left(cm\right)\)

Cạnh hình vuông lớn là: \(76:4=19\left(cm\right)\)

Cạnh hình vuông nhỏ là: \(60:4=15\left(cm\right)\)

Diện tích hình vuông lớn là: \(19\times19=361\left(cm^2\right)\)

Diện tích hình vuông nhỏ là: \(15\times15=225\left(cm^2\right)\)

\(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|\dfrac{-2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}-\dfrac{1}{5}\right)\)

\(=\dfrac{-5}{7}.\dfrac{21}{10}.\left(\dfrac{-3}{2}\right)-\dfrac{3}{4}.\dfrac{56}{9}+\dfrac{10}{3}.\dfrac{2}{15}\\ =\dfrac{9}{4}-\dfrac{14}{3}+\dfrac{4}{9}\\ =-\dfrac{71}{36}\)

\(\dfrac{4}{5}\left(\dfrac{1}{2}+\dfrac{1}{3}\right):\left(\dfrac{-3}{2}\right)+\left|\dfrac{-7}{4}\right|:\dfrac{21}{8}+\dfrac{5}{3}\left(\dfrac{3}{2}-\dfrac{6}{5}\right)\\ =\dfrac{4}{5}.\dfrac{5}{6}.\left(\dfrac{-2}{3}\right)+\dfrac{7}{4}.\dfrac{8}{21}+\dfrac{5}{3}.\dfrac{3}{10}\\ =-\dfrac{4}{9}+\dfrac{2}{3}+\dfrac{1}{2}\\ =\dfrac{13}{18}\)

\(\dfrac{15}{22}\left(\dfrac{1}{5}-\dfrac{7}{10}\right):\left(\dfrac{-2}{11}\right)+\left|\dfrac{-7}{4}\right|:\left(\dfrac{-8}{21}\right)+\dfrac{3}{5}\\ =\dfrac{15}{22}.\left(\dfrac{-1}{2}\right).\left(\dfrac{-11}{2}\right)+\dfrac{7}{4}.\left(\dfrac{-21}{8}\right)+\dfrac{3}{5}\\ =\dfrac{15}{8}-\dfrac{147}{32}+\dfrac{3}{5}\\ =-\dfrac{339}{160}\)

\(-\dfrac{17}{14}:\left(\dfrac{-34}{7}\right)+\dfrac{10}{3}\left(\dfrac{1}{5}-\dfrac{3}{4}\right)-\dfrac{6}{5}\left(\dfrac{1}{3}-\dfrac{5}{6}\right)\\ =-\dfrac{17}{14}.\left(\dfrac{-7}{34}\right)+\dfrac{10}{3}.\left(\dfrac{-11}{20}\right)-\dfrac{6}{5}.\left(\dfrac{-1}{2}\right)\\ =\dfrac{1}{4}-\dfrac{11}{6}+\dfrac{3}{5}\\ =-\dfrac{59}{60}\)