(2х-21)^2-5(2х-21)+4=0

Question

(2х-21)^2-5(2х-21)+4=0

Answer 1

4х²-84х+441-10х+105+4=0
4х²-94х+550=0
D=b²-4ac=(-94)²-4*4*550=8836-8800=36
x1=(-b+√D)/2 = (94+6)/8 = 12.5
x2=(-b-√D)/2 = (94-6)/8 = 11