We perform the quadratic formula on a quadratic equation on y:
y = -59x ± √(59²x² + 240x²) = -59x ± √(3481x²+240x²) = -59x ± √3721x²
-30 -30 -30
= -59x ± 61x = -x/15 or 4
-30
So we have (y+x/15)(y-4x)
So we multiply the other by 15 and the other by -1 since we have -15y²
4x²+59xy-15y² = (15y+x)(4x-y)
