Решите уравнения

1) (4x-3) (4x+3) - (4x-1) ^2=3x

2) 3 (x-1) ^2-3x (x-5) = 21

3) 10 (x-2) ^2 - 5x (2x-1) = - 4

4) (5x+6) ^2 - (5x-6) ^2 = 13

1) (4 х-3) (4 х+3) - (4 х-1) ^2=3 х

16 х^2-9 - (16 х^2-8 х+1) = 3 х

16 х^2-9-16 х^2+8 х-1=3 х

5 х=10

х=2

2) 3 (х-1) ^2-3 х (х-5) = 21

3 (х^2-2 х+1) - 3 х^2+15 х=21

3 х^2-6 х+3-3 х^2+15 х=21

9 х=18

х=2

3) 10 (х-2) ^2-5 х (2 х-1) = - 4

10 х^2-40 х+40-10 х^2+5 х=-4

-35 х=-44

х=44/35

4) (5 х+6) ^2 - (5 х-6) ^2=13

25 х^2+60 х+36-25 х^2+60 х-36=13

120 х=13

х=13/120