Question

Упростите выражение:
(R-3)(R+3)+(2-R)во второй степени-2R(R-2)

Answer 1

(R - 3)( R +3) + ( R - 2)^2 - 2R(R - 2) =
= (R)^2 - (3)^2 + (R^2 - 4R + 4) - 2R^2 + 4R = 
= R^2 - 9 + R^2 - 4R + 4 - 2R^2 + 4R =
= 2R^2 - 5 + 4R - 4R - 2R^2 =  
= - 5