Hello

I tried to explain the use of quadratic formula in detailed in the previous post. The solution would be pretty similar to what i have earlier answered to your problem

2x^2-7x+4=0

a=2 b=-7 and c=4 just use the method in my previous answer to your question and you will get the answers
Put this value in the standard formula to get the answer

Click the link below for earlier solution

http://www.mytutoronline.com/forum/viewtopic.php?t=112
Let me know if you have any specific problem in this regard