(x+4)²-(x-2)(x+2)=(x)²+2×x×4+(4)²-(x²+2x-2x-4)=x²+8x+16-x²+4=8x+16+4=8x+20

(х+4)²-(х+2)(х-2)= х²+8х+16 - (х²-4) = х²+8х+16 - х²+4 =8х+20