Algebra
posted by Amy on .
I've been trying to figure out this equation for over an hour but all the answers I get are wrong. The equation is 0.9=10I^2+6I . The answer is supposed to be 0.3 and it does work out, but I have tried all different ways to solve for I and nothing seems to work. Could someone please help me?

I assume you know how to complete the square
10 x^2 + 6 x = 0.9
x^2 .6 x = 0.09
x^2 .6 x + .09 = .09+.09 = 0
(x.3)^2 = 0
x = .3 sure enough. 
x^2 .6 x = 0.09 or just rearrange and factor
x^2  .6 x + 0.09 = 0
(x.3)(x.3) = 0
x = .3 and x = .3 
oh, I forgot to thank you, so thank you very much!

oh, that makes it so much easier! Thank you so very much, it all makes sense now! :D

oh, okay, I see what you're doing. I just have one question, though;why is it that when you get rid of the 10, the 6 is affected by it? I would assume that it would be left alone...

Or use quadratic equation
10 x^2 + 6 x = 0.9
10 x^2 + 6 x .9 = 0
a = 10
b = 6
c = .9
x = [6 +/ sqrt (3636) ]/20
=6/20
=3/10
= 0.3 
I divided both sides of the equation  ALL TERMS by 10

10 x^2 + 6 x

10
= x^2 .6 x 
oh, no wonder nothing worked out; thanks!