Question

find the value of 20 square - 19 square​

Answer 1

Answer:

20×20 - 19×19

= 400 - 361

= 39

Answer 2

By using identity a^2 - b^2

$a {}^{2} - b {}^{2} = (a + b)(a - b)$

$20 {}^{2} - 19 {}^{2}$

$= > 20 {}^{2} - 19 {}^{2} = (20 + 19)(20 - 19) \\ = 39 \times 1 = 39$

Hence, 39 should be the answer.