SOLUTION: x^2-4x-21=0
we must find Δ in oder to know in which conditions this equation must be solved.
Δ=((-b)^2-4*a*c)
(*)if Δ>0 this equation has 2 solutions x=(-bą√
Algebra ->
Quadratic-relations-and-conic-sections
-> SOLUTION: x^2-4x-21=0
we must find Δ in oder to know in which conditions this equation must be solved.
Δ=((-b)^2-4*a*c)
(*)if Δ>0 this equation has 2 solutions x=(-bą√
Log On
Question 235864: x^2-4x-21=0
we must find Δ in oder to know in which conditions this equation must be solved.
Δ=((-b)^2-4*a*c)
(*)if Δ>0 this equation has 2 solutions x=(-bą√Δ)/2a.
(**)if Δ=0 this equation has only one solution x=-b/2a.
(***)if Δ<0 this equation must be solved by a transformation of Δ to a complex number.
if we apply Δ's formula:
Δ=(-(-4))^2-4*(-21)=100 then Δ>0 so we must refered to condition(*)in oder to solve this equation.
√Δ=10
this equation has 2 results x1,x2.
x1=(-(-4)-10)/2; x2=(-(-4)+10)/2
x1=-3;x2=7
(
