(a-10)² tolong bantu jwb

(a-10)²=(a-10)(a-10)
={(a×a)+(a×-10)}+{(-10×a)+(-10×-10)}
=a²+(-10a)+(-10a)+100
=a²-20a+100

(a-10)(a -10) = a^2 -10a - 10a + 100
= a^2 - 20a +100