3) 24-(3y+1)(4y-5)=(11-6y)(2y-1)+6 ;
24 - (3y*4y- 3y*5 +1*4y -1*5) =(11*2y -11 -6y*2y +6y*1)+6 ;
24 - (12y² - 15y+ 4y -5) =(22y -11 -12y² +6y)+6 ;
24 - (12y² - 11y -5) =(28y -11 -12y²)+6 ;
24 - 12y² + 11y+5 =28y -11-12y² +6 ; * * * -12y² сокращаются * * *
11y+29 =28y -5 ; * * * -12y² сокращаются * * *
29+5 = 28y -11y ;
34 =17y ;
y =2.
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1) (x+1)(x+2) =(x-3)(x+4) ;
x² +2x+x+2 =x² +4x-3x -12;
3x +2 =x -12 ;
3x -x = -12 -2 ;
2x = -14 ;
x = (-14)/2 ;
x= -7.
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2) (3x-2)(2x+7) -(x+1)(6x-5) =16 ;
6x² +21x -4x-14 -(6x²-5x+6x-5) =16 ;
6x² +21x -4x-14 -6x²+5x-6x+5 =16 ;
21x -4x+5x-6x16x =16+14 -5 ;
16x =25 ;
x =25/16 * * * 1 9/16 * * *
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4) (6y +2)(5-y)=47-(2y-3)(2y-1) ;
-6y² +28y +10 = 44- 4y² +8y ;
0 =6y² -4y² -28y +8y -10 +44 ;
2y² -20y+34 =0 ;
2(y² -10y +17) =0 ;
y² -10y +17 =0 ;
y =5 ±√(25-17) ;
y =5 ±√8 ;
y₁ =5 -2√2.
y₂ =5+ 2√2.