how do you solve quadratic equations by finding square roots
i have no clue how to do this. I have fallen behind in my math class because my teacher is horrible. I need to learn this to understand everything in the section in the section. I beg someboody to answer this question. i don't want any replys like figure it out yourself or coments like ms. sue has ben posting as `answers'.Pleeaseeeeee!
<3 converse
algebra 2
an addition to my question, how would you solve somthing like 2(radical sign)2
2 answers
http://www.jiskha.com/display.cgi?id=1259619516
perhaps you mean by using the quadratic equation:
if
a x^2 + b x + c = 0
a,b, c constant, x variable
then
x = [-b +/- sqrt (b^2-4ac) ] / ( 2 a )
You can prove that by completing the square
x^2 + (b/a) x = -c/a
x^2 +(b/a) x + (b/2a)^2 = -c/a + b^2/4a^2
(x+b/2a)^2 = -4ca/4a^2 + b^2/4a^2
x + b/2a = (1/2a)sqrt( b^2 - 4ac)
if
a x^2 + b x + c = 0
a,b, c constant, x variable
then
x = [-b +/- sqrt (b^2-4ac) ] / ( 2 a )
You can prove that by completing the square
x^2 + (b/a) x = -c/a
x^2 +(b/a) x + (b/2a)^2 = -c/a + b^2/4a^2
(x+b/2a)^2 = -4ca/4a^2 + b^2/4a^2
x + b/2a = (1/2a)sqrt( b^2 - 4ac)
3 answers