Oblicz
(x-5)^2-(x+4)^2
źródło:
(x-5)^2-(x+4)^2=
=x^2-10x+25-(x^2+8x+16)=
=x^2-10x+25-x^2-8x-16=-18x+9
Wzór
(a-b)^2=a^2-2ab+b^2
(a+b)^2=a^2+2ab+b^2