the number of positive roots is the number of changes of signs there are, then decrease by 2 each time and stop when you get to 1 or 0
negative roots, sub every x with -x and reevaluate, count change of signs
decrease by 2 each time and stop when you get to 1 or 0
y=+2x⁵-x⁴-2x³+4x²+x-2
+,-,-,+,+,-
1 2 3
3 or 1 positive roots
replace x with -x ( baically flip all signs of odd powerd numbers)
y=-2x⁵-x⁴+2x³+4x²-x-2
-,-,+,+,-,-
1 2
2 or 0 negative roots
3 or 1 positive roots
2 or 0 negative roots
2nd option is answer
