ВАРИАНТ 9 1) 15х2 + 4 = 16х 2) 7х2 = 4х – 3 3) 2х – 5х2 = 0 4) 5х2 – 20 = 0 5) 7х + 3 + 4х2 = 0 6) х2 – 9х + 18 = 0 7) 16k2 + 9 – 24k = 0

15x²+4=16x 15x²-16x+4=0 D=16²-4*15*4=256-240=16 x=(16+4)/2*15=20/30=2/3 x=(16-4)/2*15=12/30=2/5 7x²=4x-3 7x²-4x+3=0 D=4²-4*7*3<0 => x∈∅ 2x-5x²=0 x(2-5x)=0 x=0, 2-5x=0 x=0, 5x=2 x=0, x=0,4 5x²-20=0/:5 x²-4=0 x²=4 x=2, x=-2 7x+3+4x²=0 4x²+7x+3=0 a-b+c=0 (4-7+3=0) => x=-1, x=-3/4=-0,75 x²-9x+18=0 D=9²-4*18=81-72=9 x=(9+3)/2=12/2=6 x=(9-3)/2=6/2=3 16k²+9-24k=0 16k²-24k+9=0 D=24²-4*16*9=576-576=0 k=24/2*16=24/32=6/8=3/4=0,75

1) 15x² - 16x + 4 = 0 D = 256 - 240 = 16 x₁ = (16+4)/30 = 2/3 x₂ = (16-4)/30 = 0,4 2) 7x²- 4x + 3 = 0 D = 16 - 84 < 0 не имеет решений в действительных числах 3) x(2 - 5x) = 0 x₁ = 0 x₂ = 0,4 4) 5x² - 20 = 0 x² = 4 x₁ = -2 x₂ = 2 5) 4x² + 7x + 3 = 0 D = 49 - 48 = 1 x₁ = (-7-1)/8 = -1 x₂ = (-7+1)/8 = -6/8 = -3/4 = -0,75 6) x² - 9x + 18 = 0 D = 81 - 72 = 9 x₁ = (9-3)/2 = 3 x₂ = (9+3)/2 = 6 7) 16k² - 24k + 9 = 0 (4k - 3)² = 0 x = 3/4 = 0,75