621)упростите . (a+3)2+(a-3)2. 2) (4a+b)2-(4a-b)2​

ab-4a=a(b-4)

a=2, b= -1

2*( -1 - 4)= - 2*5= -10

2a+3ab=a(2+3b)

a= -1, b=0

-(2+3*0)= - 2

ba-3a+1=a(b -3+1)=a(b-2)

a=1, b=2

2-2=0

2ab+3b -1=b(2a+3)-1

a=2, b= -1

-1*(2*2+3) -1= - 8

a-4ab+2=a(1-4b)+2

a=0, b= -3

0*(1-4b)+2=2

a+2b -ab=a(1-b)+2b

a=1, b= -3

(1+3) -2*3=4-6= -2

ab-4a -2b=b(a-2) -4a

a=4, b= -1

-(4-2) -4*4= - 2 -16= -18

a+ab+b=a+b(a+1)

a=1, b= -1

1 - (1+1)= -1

Объяснение: