А). -4x^5+y^2*3xy^4= -4x^5+3xy^6; б). (-3x^2y^3)^2=9x^4y^6.
Решение
S₁₄ = 105
a₄ = 88
a₄ = a₁ + d(n - 1)
Sn = {2a₁ + d(n - 1)] *n} / 2
Составим и решим систему уравнений:
a₁ + 3d = 88
(2a₁+ 13d)*14 = 2*105
a₁ + 3d = 88
<span>2a₁+ 13d = 210/14
</span><span>a₁ = 88 - 3d </span>
2a₁+ 13d = 15
2*(88 - 3d) + 13d = 15
176 - 6d + 13d = 15
7d = - 161
d = - 23
Ответ: <span>d = - 23</span>
<span>при :</span> <span>
</span><span>=3у+4+у-5-2у+1=2у+1-1=2у У=1/2, 2*1/2=1</span>