Решите уравнения 50 1) 5x^2+4x-1=0 2) 16x^2-2x-5=0 3)28x^2-36x+11=0 4) -49x^2+21x-2=0

1. D=16+20=36.
x1,2=-4±√36 / 10.
x1=-4+6 / 10 = 0,2.
x2=-4-6 / 10 = -1.

2. D=4+320=324.
x1,2=2±√324 / 32.
x1=2+18 / 32 = ⅝.
x2=2-18 / 32 = -½.

3. D=1296-1232=64.
x1,2=36±√64 / 56.
x1=36+8 / 56 = 11/14.
x2=36-8 / 56 = ½.

4. D=441-392=49.
x1,2=-21±√49 / -98.
x1=-21+7 / -98 = 1/7.
x2=-21-7 / -98 = 14/49.