Question 736771
See the web site below for additional explanation:
http://www.mathsisfun.com/algebra/intermediate-value-theorem.html
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p(x)=2x^3-9x^2+4x+15
.
p(-2)=2(-2)^3-9(-2)^2+4(-2)+15
p(-2)=2(4)-9(4)+(-8)+15
p(-2)=8-36-8+15
p(-2)=-36+15
p(-2)=-21  (negative)
.
p(0)=2(0)^3-9(0)^2+4(0)+15
p(0)=0-0+0+15
p(0)=15
.
Since p(-2) is NEGATIVE the function MUST cross y=0 to get to p(0).  Because p(0) is POSITIVE.