1. х-7≠0 (на ноль делить нельзя)
x≠7
2. 1) = 2a^3/5b
2) = 3x(4y - 1)/ 3xy = 4y-1/y
3) = (y-2)(y+2)/3(y+2) = y-2/3
4) = (4-x)(4+x)/ (x+4)²
3. 1) = x²-3x/ 3x^3 - 21-7x/3x^3 = x² - 3x- 21+7x/ 3x^3 = x² + 4x - 21/3x^3
2) 36/a(a+3) - 12/a = 36 - 12a - 36/a(a+3) = -12a/a(a+3) = -12/a+3
3)a² - a² -5a/(a-5)(a+5) = -5a/(a-5)(a+5)
4) 20x² - 20x² +35x/ 4x-7 = 35x/4x-7