Question

(a-3)²
(2y+5)²
(4a-b)(4a+b)
(x²+1)(x²-1)

Answer 1

(a-3)²=a²-6a+9
(2y+5)²=(2y)²+2*2y*5+5²=4y²+20y+25
(4a-b)(4a+b)=(4a)²-b²=16a²-b²
(x²+1)(x²-1)=(x²)²-1²=x⁴-1