a) (7x-1)(2-x) = (x-3)(3-7x)14x - 7x^2 - 2 + x = 3x - 7 - 21x + 21x^214x - 7x^2 - 2 + x = -30
-7x^2 + 15x - 2 = -30-7x^2 + 15x + 28 = 0
б) (a-3)(a+4) - (a+2)(a+7) при a = -1/8(-1/8 - 3)(-1/8 + 4) - (-1/8 + 2)(-1/8 + 7)(-25/8)(31/8) - (-15/8)(55/8)-775/64 + 825/6450/64 = 25/32
в) (m-n+10)(m+n)m^2 - mn + 10m + mn - n^2 + 10nm^2 - n^2 + 10m + 10nm^2 - n^2 + 10(m + n)
a) (7x-1)(2-x) = (x-3)(3-7x)
14x - 7x^2 - 2 + x = 3x - 7 - 21x + 21x^2
14x - 7x^2 - 2 + x = -30
-7x^2 + 15x - 2 = -30
-7x^2 + 15x + 28 = 0
б) (a-3)(a+4) - (a+2)(a+7) при a = -1/8
(-1/8 - 3)(-1/8 + 4) - (-1/8 + 2)(-1/8 + 7)
(-25/8)(31/8) - (-15/8)(55/8)
-775/64 + 825/64
50/64 = 25/32
в) (m-n+10)(m+n)
m^2 - mn + 10m + mn - n^2 + 10n
m^2 - n^2 + 10m + 10n
m^2 - n^2 + 10(m + n)