Question

помогите пж мне не понятно

Answer 1

Ответ:

2х²+13х+20=0

а=2, b=13, с=20

D=b²-4ac

D=13²-4*2*20=169-160=9=3²

x₁=(-b+√D)/2a=(-13+3)/(2*2)=-10/4=-2,5

x₂=(-b-√D)/2a=(-13-3)/(2*2)=-16/4=-4

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$\displaystyle\\(2\frac{3}{8} +\frac{11}{12} ):\frac{5}{48} =(2\frac{9}{24} +\frac{22}{24}) :\frac{5}{48}=2\frac{31}{24} :\frac{5}{48}=\frac{79*48}{24*5} =\frac{79*2}{5} =\frac{158}{5} =31,6$

Answer 2

$1)\ \ 2x^2+13x+20=0\\\\D=b^2-4ac=13^2-4\cdot 2\cdot 20=9>0\ \ ,\\\\x_1=\dfrac{-b-\sqrt{D}}{2a}=\dfrac{-13-3}{4}=-4\ \ ,\ \ x_2=\dfrac{-b+\sqrt{D}}{2a}=\dfrac{-13+3}{4}=\dfrac{-10}{4}=-2,5$

$2)\ \ \Big(2\dfrac{3}{8}+\dfrac{11}{12}\Big):\dfrac{5}{48}=\Big(\dfrac{19}{8}+\dfrac{11}{12}\Big)\cdot \dfrac{48}{5}=\dfrac{3\cdot 19+2\cdot 11}{24}\cdot \dfrac{48}{5}=\\\\\\=\dfrac{79}{24}\cdot \dfrac{48}{5}=\dfrac{79\cdot 2}{5}=\dfrac{158}{5}=31,6$