СРОЧНО!!УМОЛЯЮ!!! 1. (5+4x)^2=(9-21x)(4x+5) 2. 8(x-2)(x^2-1)=(4x^2-2x+1)(2x+1) 3....

Question

СРОЧНО!!УМОЛЯЮ!!!

1. (5+4x)^2=(9-21x)(4x+5)

2. 8(x-2)(x^2-1)=(4x^2-2x+1)(2x+1)

3. x^3-3x^2-3x+9=0

4. 2x^3-x^2-8x+4=0

5. 2x^2(2x-5)+x(2x-5)+(5-2x)=0

Answer 1

 

1)  (5+4x)^2=(9-21x)(4x+5)

      25+40x+16x^2=-84x^2-69x+45

      25+40x+16x^2+84x^2+69x-45=0

      100x^2+109x-20=0

       D=b^2-4ac=109^2-(-4*(100*20))=19881

       x1= -109-корень из 19881/200= -5/4

       x2= -109+корень из 19881/200= 4/25 

 

       

Answer 2

1. (5+4x)^2=(9-21x)(4x+5)

25+40+16^2=36x-84x^2-105x+45

100x^2-109x=20

x(100x-109)=20

x=20 100x-109=20

         100x=129

          x=1,29

2.8(x-2)(x^2-1)=(4x^2-2x+1)(2x+1)

8x^3-16x^2-8x+16=8x^3-4x^2+2x+4x^2-2x+1

-16x^2-8x=-15

-4x(4x-2)=-15

-4x=-15   4x-2=-15

x=3,75    4x=-13

               x=-3,25