The sides of 14 Squares are 11 cm, 12 cm, 13 cm, .......... 24 cm, then find the total area of 14 squares.
3515 cm 2
4515 cm 2
2115 cm 2
3215 cm 2
Explanation:
$\dfrac{n(n+1)(2n+1)}{6}$
$Area of square=a^{2}$
$11^{2}+12^{2}+13^{2}+...+24^{2}$
$=[1^{2}+2^{2}+3^{2}+....+24^{2}]-[1^{2}+2^{2}+3^{2}+...+10^{2}]$
$=\dfrac{24\times25\times49}{6}-\dfrac{10\times11\times21}{6}$
$=4900-385$
$=4515$