1)x^2-5x=14
x^2-5x-14 = 0
D = ( – 5)2 – 4·1·( – 14) = 81
x1 = 5 + √ 81/2*1 = 5 + 9/2 = 14/2 = 7
x2 = 5 – √ 81/2*1 = 5 – 9/2 = -4/2 = -2
2)9+4x^2-12x=0
4x^2-12x+9 = 0
D = ( – 12)^2 – 4·4·( + 9) = 0
x1 = 12 + √ 0/2*4 = 12 + 0/8 = 12/8 = 3/2
x2 = 12 – √ 0/2*4 = 12 – 0/8 = 12/8
3) 2x2-9x-5=0
2x2-
9x-5 = 0
D = ( – 9)2 – 4·2·( – 5) = 121
x1 = 9 + √ 121/2*2 = 9 + 11/4 = 20/4 = 5
x2 = 9 – √ 121/2*2 = 9 – 11/4 = -2/4 = -1/2
4) 3+4x^2-x=0
4x^2-x+3 = 0
D = ( – 1)^2 – 4·4·( + 3) = -47
D < 0 не имеет корней
5)x^2+x=0
x^2+x = 0
x(x) = 0
x1 = 0
x = 0
x2 = -1
6)8-2c^2=0
-2c^2+8 = 0
2c^2-8 = 0
2c^2 = 8
c^2 = 4
x1 = 2
x2 = – 2