Yahoo Answers: Answers and Comments for Solve for r.......................? [Mathematics]
Copyright © Yahoo! Inc. All rights reserved.
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
From Jasmine
enUS
Fri, 13 Aug 2010 10:48:36 +0000
3
Yahoo Answers: Answers and Comments for Solve for r.......................? [Mathematics]
292
38
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
https://s.yimg.com/zz/combo?images/emaillogous.png

From Como: r ² + 3r  2 = 0
x = [  b ± √ ( b ²  4 a c ...
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
Fri, 13 Aug 2010 18:30:05 +0000
r ² + 3r  2 = 0
x = [  b ± √ ( b ²  4 a c ) ] / 2 a
x = [  3 ± √ ( 9 + 8 ) ] / 2
x = [  3 ± √ ( 17 ) ] / 2

From Mr. Brightside: this can be written as
r^2 + 3r  2 = 0
Now ...
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
Fri, 13 Aug 2010 17:58:27 +0000
this can be written as
r^2 + 3r  2 = 0
Now to solve this you can use the discriminat method (delta = b^2  4ac....)
But if you still haven't learnt this method, then use the method of completing the square.
r^2 + 3r + (3/2)^2  (3.2)^2 2 =0
(r + 3/2)^2 = 9/4 + 2 = 17/4
r+3/2 = +or sqrt(17/4)
r = + sqrt(17/4)  3/2
or r =  sqrt(17/4)  3/2
PS: this is actually a particular derivation of the discriminant method)

From Mike: r=3.56155 or r=0.56155
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
https://answers.yahoo.com/question/index?qid=20100813104836AAlybHI
Fri, 13 Aug 2010 17:50:42 +0000
r=3.56155 or r=0.56155