Например, так:
23²/4² - 2,5²
= (6 - 1/4)^2 - (2 + 1/2)^2
= 36 - 2*6/4 + 1/16 - 4 - 2*2/2 - 1/4
= 36 - 3 - 4 - 2 + 1/16 - 4/16
= 27 - 3/16
= 26 13/16
Например, так:
23²/4² - 2,5²
= (6 - 1/4)^2 - (2 + 1/2)^2
= 36 - 2*6/4 + 1/16 - 4 - 2*2/2 - 1/4
= 36 - 3 - 4 - 2 + 1/16 - 4/16
= 27 - 3/16
= 26 13/16