Find the rational roots of x4 + 8x3 + 7x2 – 40x – 60 = 0 (1 point)2, 6
–6, –2
–2, 6
–6, 2

Question

Find the rational roots of x4 + 8x3 + 7x2 – 40x – 60 = 0  (1 point)2, 6
–6, –2
–2, 6
–6, 2

anonymous · Answer

please help me!!!!

campbell_st · Answer

you can use the factor theorem 

just evaluate f(2) f(6), f(-2) and f(-6) 

whenver you get a zero answer... the you have a rational root... 

e.g. f(2) = 2^4 + 8*2^3 + 7*2^2 - 40*2 - 60 = -32

so its not x = 2

try f(-2) = (-2)^4 + 8*(-2)^3 + 6*(-2)^2 - 40*(-2) - 60 = 0

so x = -2 is a rational zero 

try f(6)  in the same manner... if it is zero then you have your 2 rational zeros... of not... then it must be -6  but just check

hope this helps

anonymous · Answer

can u help me with another question?!

campbell_st · Answer

just post it in the normal fashoin and I'll look at it

anonymous · Answer

ok thank you