alexzigg99
alexzigg99
25-04-2017
Mathematics
contestada
solve for x x2+4x-21=0
Respuesta :
mohabbasem
mohabbasem
25-04-2017
First you calculate the determinant:
d=b^2-4ac
d=4^2-4*1*(-21)=16+84=100
Because d>0 there are two solutions for x:
x_1 = (-b+√d)/2a = (-4+√100)/2*1 = 6/2 = 3
x_2 = (-b-√d)/2a = (-4-√100)/2*1 = -14/2 =-7
The solutions for x is x = 3 and x = -7
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