(х - у)^4
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Ответ:
вот 3 и 4, 2 задание не знаю
1.(10a-6b+5c-4d)-(9a-2b-4c+2d)=10a-6b+5c-4d-9a+2b+4c-2d=a-4b+9c-6d
2. сразу открываем скобки, значок ^n - степень: 5a^2-ax+x^2+3a^2+2ax-3x^2-4ax-2x^2-a^2=7a^2-ax-4x^2
3.2m^4+5m^3 n^2-mn^3+3m^4-8m^3 n^2 - 6mn^3=5m^4-3m^3 n^2-7mn^3
4. 4,6x^2 y-2,2xy+7y^2-7.8xy+3.4x^2y-7y^2= 8x^2y-10xy = 2xy(4x-5)
при х=-2 и у=3
2* (-2)*3 * (4* (-2)-5) =-12*(-8-5)=-12* (-13)=156
Решение
<span>S</span>₅ <span>= 1/2(a</span>₁ <span>+ a</span>₅<span>)•5 = 1/2(a</span>₁ <span>+ a</span>₁ <span>+ 4d)•5 = (a</span>₁ <span>+ 2d)•5
</span><span>S</span>₆₋₁₀ <span>= 1/2(a</span>₆ <span>+ a</span>₁₀<span>)•5 = 1/2(a</span>₁ <span>+ 5d + a</span>₁ <span>+ 9d)•5 = (a</span>₁ <span>+ 7d)•5
</span><span>Найдём разность этих сумм, она равна 200
</span><span>5(a</span>₁ <span>+ 2d) - 5(a</span>₁ <span>+ 7d) = 200</span><span>a</span>₁ <span>+ 2d - a</span>₁ <span>- 7d = 40
</span><span>- 5d = 40
</span><span>d = - 8
</span><span>Аналогично найдём разность суммы с 1 по 10 и с 11 по 20
</span><span>10•1/2(а</span>₁ <span>+ а</span>₁₀<span>) - 10•1/2(а</span>₁₁ <span>+ а</span>₂₀<span>) =
</span><span>= 5(a</span>₁ <span>+ a</span>₁ <span>+ 9d) - 5(a</span>₁ <span>+ 10d + a</span>₁ <span>+ 19d) = 5(9d - 29d) =
= 5(- 20d) =</span><span> 5(- 20)*(- 8) = 800
</span><span>Ответ: 800</span>