1. <span>2xy² - 18х = </span> 2х(<span>y² - 9) = </span> 2х(y - 3)(y + 3)
2. <span>(b-1)²(b+2) - b²(b-3) + 3</span> = (<span>b² - 2</span><span>b + 1)</span>(b+2) - <span>b³ + 3</span>b² + 3 =
= <u /><span><u>b³ +</u> 2</span>b² - 2<span>b² - 4</span>b + <span>b + 2<u /></span><u> - b³</u> + 3b² + 3 =
= - 4b + <span>b + 2</span> + 3b² + 3 = 3b² + 5<span>b + 5</span>
(7/√7=7√7/(√7)²=7√7/7=√7
(x-6)/(√x-√6)=(√x)²-(√6)²/(√x-√6)=√x+√6
(3+√6)/√3=√3(3+√6)/(√3)²=(3√3+√18)/3=(3√3+3√2)/3=√3+√2
(3+√x)/(3√x+x)=(3+√x)/√x(3+√x)=1/√x=√x/√x²=√x/x
a+2√7a+7=√a²+2√7·√2+√7²=(√a+√7)²
(√a+√7)²/a-7