(3a+b)^2-(a+b)(a-b) при a=2 b=1/2

(3a+b)^2-(a+b)(a-b)=

=9a^2+6ab+b^2-(a^2-b^2)=

=9a^2+6ab+b^2-a^2+b^2=

=8a^2+6ab+2b^2=

при а=2 и b=0.5

=8*2^2+6*2*0.5+2*0.5^2=

=8*4+6+2*0.25=

=32+6+0.5=

=38.5

Ответ:

38,5

Изъясненье:

9а+6ab+b-a+b=8a+6ab+2b=2(4a+3ab+b)

2*(4+3*2*1/2+(1/2))=2*(16+3+1/4)=2*19 1/4=2*77/4=77/2=38 1/2=38,5