<span>6x^2y + 8x^2 − 30y − 40
= 2x^2(3y + 4) - 10(3y + 4)
= (2x^2 - 10)(3y + 4)
= 2(x^2 - 5)(3y + 4)</span>
There would be 2034 students competing in 2012.
We can write a simple equation to find this answer. Let X, be the number of students starting in 2012. Then, we multiply by 0.9 and 1.1 to get to 2014. To work backwards, just divide by 1.1, then by 0.9.
2014 / 1.1 / 0.9 = 2034
658,008 i just looked it up and thats what i found.
Write x-4 instead of y.
x²+(x-4)²=40
x²+x²-8x+16=40
2x²-8x-24=0
x²-4x-12=0
(x-6)(x+2)=0
x=6 or x=-2
for x=6, y=6-4 = 2
for x=-2, y=-2-4 = -6
