При каком значении? ( картинка)

можно по-разному... 1) D=14²-4*5*q = 196-20q x₁ = (14-√(196-20q))/10 x₂ = (14+√(196-20q))/10 x₂ > x₁ x₂ = 2.5x₁ (14+√(196-20q))/10 = 2.5*(14-√(196-20q))/10 14+√(196-20q) = 35-2.5√(196-20q) -21 = -3.5√(196-20q) √(196-20q) = 6 196-20q = 36 20q = 160 q = 8 ------------------- можно по т.Виета... 2) 5x² - 14x + q = 0 --->   x² - 2.8x +(q/5) = 0 { x₁*x₂ = q/5 { x₁+x₂ = 2.8 ----------------- { x₁ * 2.5x₁ = q/5 { x₁ + 2.5x₁ = 2.8 ----------------------- { 12.5*(x₁)² = q { 3.5 * x₁ = 2.8 x₁ = 28/35 = 4/5 = 0.8 q = 12.5 * 16 / 25 = 16*0.5 = 8