Question

Calculaţi:
(1 1/5)²-(7/10)²+(1 1/5-7/10)²​

Answer 1

$\it (a-b)^2+(a+b)^2=a^2-2ab+b^2+a^2+2ab+b^2=2(a^2+b^2)\\ \\ \Big(\dfrac{11}{5}- \dfrac{7}{10} \Big)^2 +\Big(\dfrac{11}{5}+\dfrac{7}{10} \Big)^2=2\Big(\dfrac{^4)121}{\ 25}+ \dfrac{49}{100} \Big)=2\cdot\Big(\dfrac{484}{\ 100}+ \dfrac{49}{100} \Big)=\\ \\ \\ =2\cdot\dfrac{533}{100}=\dfrac{533}{50}$