x²-5x-14 = 0
Проверка :
x²-5x-14 = 0
7²-5*7-14 = 0
49-35-14 = 0
14-14 = 0
0 = 0
x²-5x-14 = 0
(-2)²-5*(-2)-14 = 0
4+10-14 = 0
14-14 = 0
0 = 0
Sin(arccosx)=√(1-x²)
6√7sin(arccos(√2/3))=6√7*√(1-2/9)=6√7*√7/3=2*7=14
x^3-5x^2-4x+20=0
x^2(x-5)-4(x-5)=0
(x^2-4)(x-5)=0
x^2-4=0 ; x-5=0
x^2=4 ; x=5
x = +-2 ; x =5
Ответ: 2;-2;5