х3-125=(х-5)(х2+5х+25)
27+а3=(3+а)(9-3а+а2)
64а3-8в3=(4а-2в)(16а2+8ав+4в2)
1)
1. 3x²y⁴ + 9xy³ = 3xy³(xy + 3)
2. x² - 7x - 8 = x² - 8x - 8 + x = x(x + 1) - 8(x + 1) = (x - 8)(x + 1)
3. 9x²y - y²b + 9x²b - yb² = 9x²(y + b) - yb(y + b) = (9x² - yb)(y + b)
4. x(x - 1) + (1 - x) = x² - x + 1 - x = x² - 2x + 1 = (x - 1)²
2)
64⁸ + 16¹¹ ··· 17
8¹⁶ + 4²² ··· 17
2⁴⁸ + 2⁴⁴ ··· 17
2⁴⁴(2⁴ + 1) ··· 17
2⁴⁴(16 + 1) ··· 17
2⁴⁴ * 17 ··· 17
Если один из множителей делится на 17, значит и число делится на 17
3)
139 * 15 + 18 * 139 + 15 * 261 + 18 * 261 =
15(139 + 261) + 18(139 + 261) =
(15 + 18)(139 + 261) =
33 * 400 = 13200
1)
Треугольник Паскаля k (1) = 1, k (2) = 5, k (3) = 10, k (4) = 10, k (5) = 5, k (6) = 1
C0/5=C5/5=1
C1/5=C4/5=5!/1!4!=5
C2/5=C3/5=5!/3!2!=1*2*3*4*5/1*2*3*1*2=120/12=10
(x-1) ^5 = x^5-5x^4+10x3-10x2+5x-1
(x+1) ^7
2) Треугольник Паскаля k (1) = 1, k (2) = 7, k (3) = 21, k (4) = 35, k (5) = 35, k (6) = 21, k (7) = 7, k (8) = 1
C0/7=C7/7=1
C1/7=C6/7=7!/1!6!=7
C2/7=C5/7=7! (5!2!) = 1*2*3*4*5*6*7/1*2*3*4*5*1*2=5040/240=21
C3/7=C4/7=7!/3!2!=1*2*3*4*5*6*7/1*2*3*4*1*2*3=5040/144=35
x^7+7x^6+21x^5+35x^4+35x^3+21x^2+7x+1
1) х³-125= х³-5³=(х-5)(х²+5х+25)
2)27+а³=3³+а³=(3+а)(9-3а+а²)
3)64а³-8в³=(4а)³-(2в)³=(4а-2в)(16а²+8ав+4в²)