Question

Choose the right answers from the options given for each of the following questions.
The difference of the squares, (61² – 51² ) is equal to .................. .
(i) 1120
(ii) 1230
(iii) 1240
(iv) 1250

Answer 1

(61² – 51² )
$$\begin{gathered} =\left(61-51\right)\left(61+51\right)\left(\because \left(a^2-b^2\right)=\left(a+b\right)\left(a+b\right)\right) \\ =10\times 112 \\ =1120 \end{gathered}$$
Hence, the correct answer is option (i).