выполните умножение 1)(a²-5)(a²+5) 2)(4-x²)(4+x²) 3)(9x-y²)(9x+y²) 4)(5a2-3b)(5a2+3b) 5)(4m²+6n)(4m²-6n) 6)(1.3ab-1.1c)(1.13ab+1.1c)