The given equation is x(3x+21) = 6
⇒3x2+21x=6⇒6x2+x=12⇒6x2+x−12=0
Comparing it with ax2 + bx + c = 0
a= 6, b = 1, c = -12
By using the formula , x = 2a−b±b2−4ac , we obtain
⇒2×6−(1)±(1)2−4×6×−12⇒12−1±1+288⇒12−1+289 or 12−1−289⇒12−1+17 or 12−1−17⇒1216 or −1218⇒34 or −23
Hence, roots of the equation are 34,−23.