+0  
 
0
320
2
avatar

The polynomial $f(x)$ has degree 3. If $f(-1) = 15$, $f(0)= 0$, $f(1) = -5$, and $f(2) = 12$, then what are the $x$-intercepts of the graph of $f$?

Guest Apr 29, 2017
 #1
avatar+7485 
+1

The polynomial $f(x)$ has degree 3. If $f(-1) = 15$, $f(0)= 0$, $f(1) = -5$, and $f(2) = 12$, then what are the $x$-intercepts of the graph of $f$?

 

\(f(x)=y=ax^3+bx^2+cx+d\)

 

\(P_1(-1/15)\\P_2(0/0)\\P_3(1/-5)\\P_4(2/12)\)

 

\(y=ax^3+bx^2+cx+d\)

 

\(15=-a+b-c+d\)                     

\(0=d\)

\(-5=a+b+c +d\)

\(12=8a+4b+2c+d\)

 

a, b, c, d from the four linear equations comes slightly later.

 

laugh  !

asinus  Apr 29, 2017
edited by asinus  Apr 29, 2017
 #2
avatar+27034 
+1

a = 2, b = 5, c = -12, d = 0

Alan  Apr 29, 2017

7 Online Users

avatar

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.