GMAT Math

a whole subsection is dedicated to the quadratic equation in the OG...but has anyone ever seen a question where you actually need to calculate it out? doesn't seem like that would fit into the GMAT world of the <2minutes per questions mentality...just curious

sbburnsi wrote:a whole subsection is dedicated to the quadratic equation in the OG...but has anyone ever seen a question where you actually need to calculate it out? doesn't seem like that would fit into the GMAT world of the <2minutes per questions mentality...just curious

I have heard it said many times that GMAT questions should never require the use of the quadratic formula. Factoring of quadratic equations, however, will be tested thoroughly.

I have never stumbled across calculating the quadratic equation out using the FOIL method or anything. Rather, what my practice has led me to know is (a-b)(a-b); a^2-b^2; as well as(a+b)(a+b), and just identifying / recognizing these special quadratics.

For example:
When x is subtracted from y the result is 9 and when x is added to y the result is 10.
What is the value of x^2-y^2

The answer to this would just be (9)*(10) which is 90 = (x-y)(x+y)...

hope I was able to helps

sbburnsi wrote:a whole subsection is dedicated to the quadratic equation in the OG...but has anyone ever seen a question where you actually need to calculate it out? doesn't seem like that would fit into the GMAT world of the <2minutes per questions mentality...just curious

When I did a search of the OG, I only found one mention of the quadratic formula, on p.124, where they say that it can be used to find the solutions of quadratic equations that are difficult to factor. My takeaway is the the quadratic formula is not required for the GMAT, but it may be a useful backup option if you are having difficulty solving the equation by factoring.