SOLUTION: Hi, I am solving by the quadradic formula -b sqrt (b^2-4ac)/(2a) Would you show me how to finish this? 18x^2-39x+20=0 x = -39 sqrt (39)^2-4(18)(20)/(2(18)) x = -39 sqrt (15

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Hi, I am solving by the quadradic formula -b sqrt (b^2-4ac)/(2a) Would you show me how to finish this? 18x^2-39x+20=0 x = -39 sqrt (39)^2-4(18)(20)/(2(18)) x = -39 sqrt (15      Log On


   

Question 409229: Hi, I am solving by the quadradic formula -b sqrt (b^2-4ac)/(2a)
Would you show me how to finish this?
18x^2-39x+20=0
x = -39 sqrt (39)^2-4(18)(20)/(2(18))
x = -39 sqrt (1521 - 1440)/(36)
x = -39 sqrt (81)/(36)
x = (-39 - 9)/(36) lost here, what do I do?
Answer by Edwin McCravy(20086) About Me  (Show Source):
You can put this solution on YOUR website!


You have a sign wrong, and also you left out the "plus or minus", ±.

Here it is worked correctly step by step

18x%5E2-39x%2B20=0

Compare to

ax%5E2%2Bbx%2Bc=0

a=18, b=-39, c=20


x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ 



x+=+%2839+%2B-+sqrt%281521-1440%29%29%2F36+

x+=+%2839+%2B-+sqrt%2881%29%29%2F36+

x+=+%2839+%2B-+9%29%2F36+

Using the +,

x+=+%2839+%2B+9%29%2F36+

x+=+48%2F36+

x+=+4%2F3

Using the -,

x+=+%2839+-+9%29%2F36+

x+=+30%2F36+

x+=+5%2F6

Edwin