mohan514 wrote:
PIneappleBoy2 wrote:
I solved the problem using the quadratic formula, but I welcome other ways on how to do it faster.
a=1, b=1, c= -380
x= \(\frac{-1+-\sqrt{1^2-4(1)(-380)}}{2(1)}\)
x= \(\frac{-1+-\sqrt{1521}}{2}\)
x= \(\frac{-1+39}{2(1)}\) and x= \(\frac{-1-39}{2}\)
X= \(\frac{38}{2}\) and x= \(\frac{-40}{2}\)
x=14 and x=-20.
Since we are looking for a positive integer, we can disregard -20 and only look at x=14.
Quantity A = 14
Quantity B = 10
Quantity A is greater.
The answer is A.
38/2 is 19 BTW.
How do we know square root of 1521 is 39?
I think we can just consider about the symobl the number would have and conclude as positive vs negative. Correct me if I am wrong.
Also is that the only way to solve this problem?
Just edited my original post to reflect that the answer is actually 19, not 14. Thank you for that.
We are able to find that 39 is the square root of 1521 through the use of the GRE Calculator.
As for concluding the positive vs. negative, you are correct. I just wrote it out since it was a part of the quadratic equation.