solve by completing the square.
2x^2+30x-45=0

Question

solve by completing the square. 
2x^2+30x-45=0

anonymous · Answer

You have to make some attempt, or you won't be ready for test time.

anonymous · Answer

i did. and then i get stuck. 
i took the 2 out of the equation but then started to get fractions. and then that is messing it all up

chaise · Answer

2x^2+30x-45=0

In order to create a 'prefect square' you take the "30" and half it.. so "15" and then 15x15 = 225 and also add to give 30. The -270 tagged on the end is what needs to be done in order to get the equation back down to it's '-45' which is tagged on the end. The same principle is done for other quadratic's where you are trying to solve.
 
(2x^2 + 30x + 225) - 270 = 0
This number in the brackets can now be factorised very easily, then solve the equation for your 'X' value. You may need to use the quadratic formula if you are unable to answer 'X'.

Best of luck with your problem. I hope I could be helpful.

anonymous · Answer

so i dont take out the 2 first?

chaise · Answer

You may need to do that.

anonymous · Answer

Put a bracket around the first two terms and then divide out the 2.

anonymous · Answer

ok thank you