Cez005 wrote:

Hi all,

Factoring (t^2)+4t-672=0 was required for a

OG question. Any tips on how to approach this other than trial and error using the answer choices?

Hi

Cez005,

There are mainly three ways to solve the quadratic equation problems.

1. Using formula

2. Middle term factorization method, and

3. Method of completing Square

I'll explain the Method of completing Square.

Any quadratic equation of the form \(ax^{2} + bx + c = 0\) can be transformed into \(a(x+d)^{2} + e = 0\),

where \(d = \frac{b}{2a} \textrm{ and } e = c - \frac{b^{2}}{2a}\)

In the given example, we have \(a = 1, b = 4 \textrm{ and }c = -672\)

\(d = 4/2 = 2, e = -672 - 16/4 = -676\)

Hence, we have \((t + 2)^{2} - 676 = 0 \Rightarrow (t+2)^{2} = 26^{2} \Rightarrow t+2 = \pm 26 \Rightarrow t = 24 \textrm{ or } -28\)

For more detail please visit

completing-square.htmlPlease remember squares of 1 to 30.

what-to-memorize-in-gmat-quant-for-the-gmat.

Hope this helps.