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=16x15x²-16x+4=0D=16²-4*15*4=256-240=16x=(16+4)/2*15=20/30=2/3x=(16-4)/2*15=12/30=2/57x²=4x-37x²-4x+3=0D=4²-4*7*3<0 => x∈∅2x-5x²=0x(2-5x)=0x=0, 2-5x=0x=0, 5x=2x=0, x=0,45x²-20=0/:5x²-4=0x²=4x=2, x=-27x+3+4x²=04x²+7x+3=0a-b+c=0 (4-7+3=0) => x=-1, x=-3/4=-0,75x²-9x+18=0D=9²-4*18=81-72=9x=(9+3)/2=12/2=6x=(9-3)/2=6/2=316k²+9-24k=016k²-24k+9=0D=24²-4*16*9=576-576=0k=24/2*16=24/32=6/8=3/4=0,75

1)15x² - 16x + 4 = 0D = 256 - 240 = 16x₁ = (16+4)/30 = 2/3x₂ = (16-4)/30 = 0,42)7x²- 4x + 3 = 0D = 16 - 84 < 0не имеет решений в действительных числах3)x(2 - 5x) = 0x₁ = 0x₂ = 0,44)5x² - 20 = 0x² = 4x₁ = -2x₂ = 25)4x² + 7x + 3 = 0D = 49 - 48 = 1x₁ = (-7-1)/8 = -1x₂ = (-7+1)/8 = -6/8 = -3/4 = -0,756)x² - 9x + 18 = 0D = 81 - 72 = 9x₁ = (9-3)/2 = 3x₂ = (9+3)/2 = 67)16k² - 24k + 9 = 0(4k - 3)² = 0x = 3/4 = 0,75