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 .
0,399053 вот ответ к решению
B1=3; b3=12
b3=b1•q^2=3•q^2
3•q^2=12
q^2=4
q=2
b2=b1•q=3•2=6