|a| = √ 3^2+0^2+(-4)^2 = 5
Р³+27р³-108р²+144р-64=0
28р³-108р²+144р-64=0
Решение
x² + px + q = 0
По теореме Виета
x₁ + x₂ = - p; x₁ * x₂ = q
- 5 + 8 = 3
p = - 3
- 5*8 = - 40
q = - 40
x² - 3x - 40 = 0
4x-(7x-2)=60, -3x+2=60,-3x=-62, x=62/3
/BC/ = 1/5.62/3=62/15 ( cm)