Question

2x²+15 x+18 solve by completing the square

Answer 1

is this deriving?if it is then the answer is 4x+15

Answer 2

start with
\[2x^2+15x=-18\] divide by 2 and get
\[x^2+\frac{15}{2}x=-9\] then complete the square by taking half of \(\frac{15}{2}\) which is \(\frac{15}{4}\) square and add to both sides to get
\[(x+\frac{15}{4})^2=-9+(\frac{15}{4})^2\]
now some arithmetic

Answer 3

\[-9+(\frac{15}{4})^2=\frac{81}{16}\] so you get
\[(x+\frac{15}{4})^2=\frac{81}{16}\] take the root and get
\[x+\frac{15}{4}=\frac{9}{4}\] or
\[x+\frac{15}{4}=-\frac{9}{4}\]
then subtract \(\frac{15}{4}\) in both equations to solve for \(x\)

Answer 4

shouldnt their be two answwers?

Answer 5

i know one of them is -6, and rge other should be -3/2..... but how do i get that??

Answer 6

Maybe u want IT=(2x+3)*(x+6)

Answer 7

huh?? if your talking about the equation.. i cant change that! ;P

Answer 8

yes there are two answers
\[x+\frac{15}{4}=\frac{9}{4}\]
\[x=\frac{9}{4}-\frac{15}{4}=-\frac{6}{4}=-\frac{3}{2}\] is one of them

Answer 9

\[x+\frac{15}{4}=-\frac{9}{4}\]
\[x=-\frac{9}{4}-\frac{15}{4}=-\frac{24}{4}=-6\]is the other one

Answer 10

thank you sooooooooo much your a life saver!!;)