1) = ( 10a^5 )^2 - ( 1/2bc )^2 = 100a^10 - 1/4b^2c^2
2) ( 2y- 3 )( 3y + 1 ) + 2( y - 5 )( y + 5 ) = 2( 1 - 2y^2 ) + 6y
6y^2 + 2y - 9y - 3 + 2( y^2 - 25 ) = 2 - 4y^2 + 6y
6y^2 - 7y - 3 + 2y^2 - 50 = 2 - 4y^2 + 6y
8y^2 - 7y - 53 - 2 + 4y^2 - 6y = 0
12y^2 - 13y - 55 = 0
D = 169 + 2640 = 2809 = 53^2
y1 = ( 13 + 53 ) : 24 = 2,75
y2 = ( 13 - 53 ) : 24 = - 5/3 = - 1 2/3
3) ( 3x - 7 )^2 - 4x^2 = 0
9x^2 - 42x + 49 - 4x^2 = 0
5x^2 - 42x + 49 = 0
D = 1764 - 980 = 784 = 28^2
x1 = ( 42 + 28 ) : 10 = 7
x2 = ( 42 - 28 ) : 10 = 1,4
Х^-3х-4=0 или х^+3х-4=0
Д=25;х=4;х=-0,5 или Д=25;х=-4;х=0,5
ОДЗ:х^+3х-4>=0
(-~;-4];[0,5;+~)
Ответ:-4;0,5;4
12-6x-18-7x=x2+3x-2x-6
x2+12x=0
x (x+12)=0
x=o или x=-12
отает: -12 и 0
15x²-8bx+b²=15(x-b/5)(x-b/3)=(5x-b)(3x-b)
D=64b²-60b²=4b²
x1=(8b-2b)/30=b/5 U x2=(8b+2b)/30=b/3
12x²-bx-b²=12(x+b/4)(x-b/3)=(4x+b)(3x-b)
D=b²+48b²=49b²
x1=(b-7b)/24=-b/4 U x2=(b+7b)/24=b/3
(15x²-8bx+b²)/(12x²-bx-b²)=(5x-b)(3x-b)/(4x+b)(3x-b)=(5x-b)/(4x+b)
= -1 2/3
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