How do you solve #x^2 + 7x – 1 = 0#?

1 Answer
Don't Memorise
Sep 11, 2015

The solutions are
#color(blue)(x= (-7+sqrt(53))/2#
#color(blue)(x= (-7-sqrt(53))/2#

Explanation:

The equation : #x^2 + 7x -1 = 0# is of the form #color(blue)(ax^2+bx+c=0# where:

#a=1, b= 7, c= -1 #

The Discriminant is given by:
#Delta=b^2-4*a*c#
# = (7)^2-(4*(1)* -1)#
# = 49 +4 = 53#

The solutions are found using the formula
#x=(-b+-sqrtDelta)/(2*a)#

#x = (-7+-sqrt(53))/(2*1) = (-7+-sqrt(53))/2#

The solutions are
#color(blue)(x= (-7+sqrt(53))/2#
#color(blue)(x= (-7-sqrt(53))/2#

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