Question

x^2+3x-9=0 completing the square. please will appreciate if working is shown.

Answer 1

a = 1 b = 3 and c = -9
what is -b/2a =

Answer 2

can you respond?

Answer 3

sorry just got back

Answer 4

let me explain with general equation and see of that makes sense to you.

starting with
\[x^2 +bx+c=0\]
you want the equation to end up looking like
\[(x+h)^2 + k = 0\]
expanding the square:
\[x^2 +2hx +h^2 +k = 0\]
this means
\[b = 2h \rightarrow h = \frac{b}{2}\]
and
\[c = h^2 +k \rightarrow k = c - h^2\]

Answer 5

For your example;
b= 3
c = -9

so
\[h = \frac{b}{2} = \frac{3}{2}\]
\[k = c - h^2 = -9 - (\frac{3}{2})^2\]