Ответ 25000 рублей
21750 - 87% его зар.платы
знач. 21750 / 87 x 100 = 25000
А) 5(a^2 - 2ab+b^2)=5a^2-10ab+5b^2
б) 2 (m^2 - 3m+3)=2m^2-6m+6<span><span>
</span><span>в) -3 (x^2 +xy
+y^2)=-3x^2-3xy-3y^2</span><span>
</span><span>г<span>) -4(1-2n^2
-3n^3)=-4+8n^2+12n^3
</span></span></span>а) 3n^2– n (4n – 6m)=3n^2-4n^2+6nm=-n^2+6nm
б) 5а + 2а (3а – 2)=5a+6a^2-4a=a+6a^2
X² - 4x + 6 = 21/(x² - 4x + 10)
замена: х² - 4х = n
n + 6 = 21/(n + 10)
(n + 6)(n + 10) = 21
n² + 10n + 6n + 60 = 21
n² + 16n + 60 - 21 = 0
n² + 16n + 39 = 0
D = 16² - 4*1*39 = 256 -156 = 100 = 10²
D> 0
n₁ = ( - 16 - 10)/(2 * 1) = - 26/2 = -13
n₂ = (- 16 + 10)/(2 *1) = -6/2 = - 3
x² - 4x = - 13
x² - 4x + 13 = 0
D = (-4)² - 4*1*13 = 16 - 52 = - 36
D<0 нет решений
х² - 4х = - 3
х² - 4х + 3 = 0
D = (-4)² - 4*1*3 = 16 - 12 = 4 = 2²
D>0
x₁ = ( - (-4) - 2)/(2*1) = (4-2)/2 = 2/2 = 1
x₂ = ( - (-4) +2)/(2*1) = (4 +2)/2 = 6/2 = 3
Ответ : х₁ = 1 ; х₂ = 3 .
При любых значениях a, так как a^2+1 будет > 0