How do you solve #x^2-30=0# using the quadratic formula?

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Answer 1 · 2016-06-16T02:23:30

The quadratic formula requires us to put our quadratic into standard form:

#ax^2+bx+c=0#

Our quadratic is already in this form:

#x^2-30= 1x^2 + 0x -30 =0#

Therefore

#a=1," " b=0 " & " c=-30#

Then we use the quadratic formula:

#x_(+-) = (-b+-sqrt(b^2-4ac))/(2a)#

#x_(+-) = (0+-sqrt(0-4*1*(-30)))/(2*1)#

#x_(+-) = +-sqrt(120)/(2)#

we can bring the #2# from the denominator up into the square root by first squaring it

#x_(+-) = +-sqrt(120/4)=+-sqrt(30)#

Which is the answer that we would have arrived at by just moving the #-30# to the right hand side and taking the square root of both sides.