Question

if f(x)=x^3+Ax^2+Bx-3 if f(1)=4 and f(-1)=-6 what is the value of 2A+B

Answer 1

substitute in the points
f(1) = 4 .... x=1, y=4
--> A+B-3 = 4
--> A+B = 7

f(-1) = -6 ... x=-1 , y=-6
--> -1+A-B-3 = -6
--> A -B = -2

solve for A and B