1) (m-5)² = m²-10m+25
(2a+7b)² = 4a²+28ab+49b²
(a+3)(a-3)= a²-9
(8x+5y)(5y-8x) = 40xy-40xy =1
2) x² - 81= (x-9)(x+9)
y²-6y+9= (y-3)²
16x²-49= (4x-7)(4x+7)
9a2+30ab+25b²= (3a+5b)
3). (n - 6)² - (n-2)(n+2) = n² - 12n+36-(n²-4)= n²-12n+36-n²+4= 40-12n
4) (2x+5)(x-6)+2(3x+2)(3x-2)
20x²-7x-38=20x²+20x+16
-7x-20x=16+38
-27x=54
x=-2
5) (2b-1)² -(b+2)² = (2b -1 - b -2)(2b-1 +b +2) =(b-3)(3b+1)
6). (a-6)(a+6)(36-a²)-(a²-18)²= (a²-36)(a²+36)-a⁴+36a²-324=a⁴-1296-a⁴+36a²-324=36a²-1620
36(-1/6)²-1620=36 * 1/36-1620=1