Using identities solve 20.5*19.5
Answers
Answered by
15
using identity÷
(20.5-0.5) * (19.5+0.5)
=20.0 *20.0
=400
(20.5-0.5) * (19.5+0.5)
=20.0 *20.0
=400
Answered by
39
use the formula (a + b)(a -b) = a^2 - b^2 ------(i)
Given that, 20.5 * 19.5
i.e, (20 + 0.5)(20 - 0.5) (Rearranging the numbers)
i.e, 20^2 - 0.5^2 (using (i) )
i.e, 400 - 0.25
i.e, 399.75 is your required answer
Given that, 20.5 * 19.5
i.e, (20 + 0.5)(20 - 0.5) (Rearranging the numbers)
i.e, 20^2 - 0.5^2 (using (i) )
i.e, 400 - 0.25
i.e, 399.75 is your required answer
Similar questions