1. 14x⁴y/ 49x³y² = 2x/7y

2. x-y/7 - x/7 = x-y-x/7 = -y/7

3. 3a - 9/a+2 : a²-9/a²-4 = 3a-9/a+2 × a²-4/a²-9 = 3a-9/a+2 × (a-2)(a+2)/a²-9 = 3-6= -3

4. 2a/a-5 - 5/a+5 +2a²/25-a² = 2a/a-5 - 5/a+5 + 2a²/ (5-a)(5+a) = 2a/a-5 - 5/a+5 +2a²/(a-5)(a+5) = 2a(a+5) -5(a-5) +2a²/(a-5)(a+5) = 2a +10×a²+5a - 5a+25 +2a²/(a-5)(a+5) = 35+4a⁵/(a+5)(a-5)

5. 2a+b/1 - 4ab/2a+b = (2a+b)² - 4ab/2a+b = 2a+b-4ab = -8a²b² если а = 1 и b =-1 , то -8а²b² = -8×1²×(-1)² = -8×1×1 = -8

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