Write x2 + 4x = 5 in vertex form. Write your answer in the form a(x-h)^2+k=0 with no spaces

Question

solomonzelman · Answer

$\large\color{blue}{x^2 + 4x = 5    }$

$\large\color{blue}{x^2 + 4x \color{red}{+4}= 5 \color{red}{+4}   }$      Do you see a perfect square trinomial on the left hand side?

solomonzelman · Answer

essay?

anonymous · Answer

too bad your math teacher does not understand the difference between 
$$y=x^2+4x-5$$  a parabola with a vertex and 
$$x^2+4x=5$$
which is not a parabola, just an equation for which 
$$x=-5, x =1$$

solomonzelman · Answer

I was thinking of that too...

solomonzelman · Answer

This is not the first case, when the questions that schools give need revision.

anonymous · Answer

there is no end to bad math education
not really surprising since most secondary math teacher i have known thought math was something of a mystery

solomonzelman · Answer

Anyways,
As you can see, I added, 4 to both sides,

$\large\color{blue}{x^2 + 4x +4= 5 +4   }$

can you re-write the left side? (it is a perfect square trinomial)

anonymous · Answer

write them and tell them if 
$$x^2+4x=5$$ then $x=5$ or $x=-1$ and that this has no vertex because it is not  the graph of 
$$y=x^2+4x-5$$

anonymous · Answer

don't let them bulldoze you in to writing an incorrect answer just to please them

solomonzelman · Answer

well, it kind of is, it is basically a (full) function, set =0 to solve for y intercept.
But, I don't know WHY they do this, either though...

solomonzelman · Answer

@Sydniariana1 
Do you know what a perfect quare trinomial is?

solomonzelman · Answer

*square trinomial

anonymous · Answer

yes

solomonzelman · Answer

can you re-write the left side?

solomonzelman · Answer

$\large\color{blue}{x^2+4x+4 }$ is    $\large\color{blue}{x^2+2x+2x+4 }$

solomonzelman · Answer

factor that