SOLUTION: Quesion : Solve for y: y^4-4y^2=40y-10y^3 y= or y= or y= or y= Possible Answers: (a) 0, 10, 2, -2 (b) 0, -10, -2, 4 (c) 0, -10, 2, -2 (d) 0, 10, -2, -4

Algebra ->  College  -> Linear Algebra -> SOLUTION: Quesion : Solve for y: y^4-4y^2=40y-10y^3 y= or y= or y= or y= Possible Answers: (a) 0, 10, 2, -2 (b) 0, -10, -2, 4 (c) 0, -10, 2, -2 (d) 0, 10, -2, -4       Log On


   

Question 30330: Quesion : Solve for y: y^4-4y^2=40y-10y^3
y= or y= or y= or y=
Possible Answers:
(a) 0, 10, 2, -2
(b) 0, -10, -2, 4
(c) 0, -10, 2, -2
(d) 0, 10, -2, -4
Answer by Fermat(136) About Me  (Show Source):
You can put this solution on YOUR website!
y^4-4y^2=40y-10y^3
rearrange,
y^4 + 10y^3 = 4y^2 + 40y
take out y^3 and y to get (y+10) as a factor
y^3(y + 10) = y(4y + 40)
y^3(y + 10) - 4y(y + 10)
take out (y+10) as a common factor,
(y+10)(y^3 - 4y) = 0
(y+10)y(y² - 4) = 0
y = -10, 0, or y = +/- 2
y = -10, -2, 0, 2
==================
Ans: (c)
========