=(Помогите решить) Пожалуйста! ♥

1а: 2mn/(m²-n²) + (m-n)/(m+n)=2mn/((m-n)(m+n))+(m-n)²/((m-n)*(m+n))=(2mn+m²-2mn+n²)/(m²-n²)=(m²+n²)/(m²-n²)
1б: (ab-b²)/a² - (3a-3b)/a = (ab-b²-3a²+3ab)/a² = 4b/a - b²/a² - 3
2: (x-2)/5 - (x-1)/3 = 3, (3x-6-5x+5)/15 = 3, -2x-1 = 45, -2x = 46, x=-23
3: $a^{3}$ * $a^{-13}$ / $a^{-4}$ = $a^{(3-13+4)}$ = $a^{-6}$
$1/2^{-6}$ = $2^{6}$ = 64.
4: 2√3=√12, √12>√11
5: 23 * $10^{-5}$ = 2.3 * $10^{-4}$
2.3 * $10^{-4}$ < 2.7 * $10^{-4}$ < 210 * $10^{-4}$
6: ((√5+√3)² - (√5-√3)²) / ((√5-√3)*(√5+√3)) = (5 + 2√15 + 3 - 5 + 2√15 - 3) / ((√5)² - (√3)²) = 4√15 / (5 - 3) = 4√15 / 2 = 2√15