IA
Ivan Asonov
Ответ
(4+3x)^2 - 8 = 2x^2 + 39x
16 + 24x + 9x^2 - 8 = 2x^2 + 39x
(9x^2 - 2x^2) + (24x - 39x) + (16 - = 0
7x^2 - 15x + 8 = 0
x(1,2) = [15 +- V(15^2 - 4*7*8)] / 2*7 =
= [15 +- V(225 - 224)] /14 =
= (15 +- 1) /14
x(1) = (15+1) /14 = 16/14 = 8/7
x(2) = (15-1) /14 = 1
= 16 +24x +9x^2 - 8 - 2x^2 - 39x = 7x^2 - 15x - 8
7x^2 - 15x + 8 = 0
D = b^2 - 4ac = 225 - 224 = 1
x1 = -b минус корень из D\2a = 15-1\14 = 14\14 = 1
x2 = -b плюс корень из D \ 2a = 15 +1 \14 = 16\14 = 8\7