How do you solve 8x+1=4x^2 by quadratic formula?

2 Answers
Feb 7, 2016

8x+1=4x^2

rarr8x=4x^2-1

rarr4x^2-1-8x=0

In standard form:

rarr4x^2-8x-1=0

Now this is a Quadratic equation (in form ax^2+bx^2+c=0)

Use Quadratic formula:

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

In this case a=4,b=-8,c=-1

Substitute the values into the formula:

rarrx=(-(-8)+-sqrt((-8)^2-4(4)(-1)))/(2(4))

rarrx=(8+-sqrt(64-(-16)))/8

rarrx=(8+-sqrt(64+16))/8

rarrx=(8+-sqrt(80))/8

rarrx=(8+-sqrt(16*5))/8

rarrx=(8+-4sqrt5)/8

rarrx=(2+-sqrt5)/2

Feb 7, 2016

(2+-sqrt(5))/(2)

Explanation:

quadratic fomula

ax^2+bx+c=0

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

so 8x+1=4x^2

rarr4x^2-8x-1=0

rarr(-(-8)+-sqrt((-8)^2 -4(4)(-1)))/(2(4))

rarr(8+-sqrt(64 +16))/(8)

rarr(8+-sqrt(80))/(8)

rarr(8+-4sqrt(5))/(8)

rarr(8+-4sqrt(5))/(8)

rarr(2+-sqrt(5))/(2)