Question #ae88d

1 Answer
May 11, 2017

See below.

Explanation:

If the question is stated correctly as #5x^2+4=x#:

First, we move the #x# to the left-hand side by subtracting #x# from both sides to make the right-hand side equal #0#:
#5x^2-x+4=0#

Since this cannot be easily factored, we use the quadratic formula:
#x=(-b+-sqrt(b^2-4ac))/(2a)#
where #a=5,b=-1,c=4# according to the given equation
So, by substitution, we have:
#x=(1+-sqrt((-1)^2-4(5)(4)))/(2(5))#
#x=(1+-sqrt(-79))/10#
#x=(1+-isqrt(79))/10#

Since we cannot simplify this further, our solutions are:
#x=(1+isqrt(79))/10,(1-isqrt(79))/10#

If the question was intended to be stated as #5x^2-4=x#:

We follow a similar procedure:
We move the #x# to the left-hand side by subtracting #x# from both sides to make the right-hand side equal #0#:
#5x^2-x-4=0#

This can be easily factored as:
#(5x+4)(x-1)=0#
So we get that #5x+4=0# or #x-1=0# and solve for #x#:
#5x+4=0#
#x=-4/5#

#x-1=0#
#x=1#

So our solutions for this question are: #x=-4/5,1#