How do you solve #x^2-7x+8=0# using the quadratic formula?

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Answer 1 · 2018-03-27T13:45:37

#color(blue)(x=7/2+sqrt(17)/2#

#color(blue)(x=7/2-sqrt(17)/2#

For quadratics in the form:

#color(red)(ax^2+bx+c)#

#color(blue)(x=(-b+-sqrt(b^2-4ac))/(2a))#

We have:

#bba = 1#

#bb(b)=-7#

#bbc=8#

Plugging these into the formula:

#x=(-(-7)+-sqrt((-7)^2-4(1)(8)))/(2(1))#

#x=(7+-sqrt(49-32))/(2)#

#x=(7+-sqrt(17))/(2)#

#color(blue)(x=7/2+sqrt(17)/2#

#color(blue)(x=7/2-sqrt(17)/2#