yy two strokes of the second (2nd) order equally y squared y stroke first (1st) order plus (y stroke first (1st) order ) squared equally 0
yy two strokes of the second (2nd) order equally y to the power of two y stroke first (1st) order plus (y stroke first (1st) order ) squared equally zero
yy''=y2y'+(y')2=0
yy''=y2y'+y'2=0
yy''=y²y'+(y')²=0
yy''=y to the power of 2y'+(y') to the power of 2=0