Question

решите уравнение 1/2(x+2)+1/3(x+3)+1/5(x-5)=2

Answer 1

1/2(x+2)+1/3(x+3)+1/5(x-5)=2

1/2х+1+1/3х+1+1/5х-1=2

1/2х+1/3х+1/5х=2+1-1-1

х=30/31

 

 

 

 

 

 

Answer 2

15*(X+3)*(X-5) + 10*(X+2)*(X-5) +6*(X+2)*(X+3) 30*(X+2)*(X+3)*(X-5) = 2

15*(X^2-2X-15) +10*(X^2-3X-10) +6*(X^2+5X+6) = 60*(X+2)*(X+3)*(X-5)

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 15X^2 - 30X - 225 + 10X^2 - 30X - 100 +6X^2 +30X + 36 =

= 31X^2 - 30X - 289

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60*(X+2)*(X+3)*(X-5) = 60*(X^2+5X+6)*(X-5) = 60*(X^3 - 19X -30) = 60X^3 - 1140X - 1800

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31X^2 - 30X - 289 = 60X^3 - 1140X - 1800

60X^3 - 31X^2 - 1110X - 1511 = 0

Берём производную:

180X^2 - 62X - 1110X = 0  

2*(90X^2 - 31X - 555) = 0

D = 961 - 4*90*(-555) = 961 + 199800=200761   V D = 448

X1 = 31 + 448 180 = 2.6

X2 = 31 - 448 180 = - 417180 = - 2.3