second post algebra
posted by jean on .
does anyone have a clue how to do this. I am so lost. If you can please explan why you do what you do when working this out so maybe i can better understand this. thanks a bunch.
Prove (algebraically, not numerically) that the product of the solutions of
ax^2+bx+c=0 is c/a

Remember that the quadratic formula gives you the solution
x = (b ±√(b^24ac))/(2a)
so when we multiply these two solutions we get
(b+√(b^24ac))/(2a) * (b√(b^24ac))/(2a)
= (b^2  (b^24ac))/(4a^2)
= 4ac/(4a^2)
= c/a