(3x-1) (x+2)=20 решите пж

Question

(3x-1) (x+2)=20 решите пж

Answer 1

(3x-1) (x+2)=20

раскрываем скобки

3x^2 +6x-x-2 = 20

3x^2 + 5x = 20+2

3x^2 + 5x-22 = 0

a=3  b=5  c=-22

D = b^2 - 4ac = 5^2 - 4*3*(-22) = 25-(-264) = 25+264 = 289

D = 17

X1 = -b+D/2a = -5+17/2*3 = -22/6 = -11/3

X2 = -b-D/2a = -5-17/2*3 = 12/6 = 2