4. Упростите выражение: 1) a) 8(5y+3)² +9(3y-1)²; б) (2x-5)²-2(7x-1)²; 2) a) (4y²+3)²+(9-4y²)² - 2(4y²+3)(4y²-9); б) (a²-6ab+9b²)(a²+6ab+b²) – (a²-9b²)².

1) a) $$8(25y^2 + 30y + 9) + 9(9y^2 - 6y + 1) = 200y^2 + 240y + 72 + 81y^2 - 54y + 9 = 281y^2 + 186y + 81$$
1) б) $$(4x^2 - 20x + 25) - 2(49x^2 - 14x + 1) = 4x^2 - 20x + 25 - 98x^2 + 28x - 2 = -94x^2 + 8x + 23$$
2) a) Let $$A = 4y^2+3$$ and $$B = 9-4y^2$$. The expression is $$A^2 + B^2 - 2(A)(4y^2-9)$$. This does not simplify nicely without further information or correction.
2) б) $$(a-3b)^2(a+3b)^2 - (a^2-9b^2)^2 = ((a-3b)(a+3b))^2 - (a^2-9b^2)^2 = (a^2-9b^2)^2 - (a^2-9b^2)^2 = 0$$.