Question 30237: Question:
Solve for y: y^4-4y^2=40y-10y^3
y=________ or y+_________ or y= _____________ or y= _______________
Possible Answers:
(a) 1, 10, 2, -2
(b) 0, -10, -2, 4
(c) 0, -10, 2, -2
(d) 0, 10, -2, -4
Please help and be specific as to which answer is correct.
Answer by sdmmadam@yahoo.com(530)   (Show Source):
You can put this solution on YOUR website! Solve for y:
y^4-4y^2=40y-10y^3 ----(1)
(taking all the terms to the left side changin sign while changing side)
y^4+10y^3-4y^2-40y=0
y[y^3+10y^2-4y-40]=0
y[y^2(y+10)-4(y+10)] = 0
y[y^2p-4p] = 0 where p =(y+10)
yp(y^2-4)=0
y(y+10)(y+2)(y-2) = 0
Therefore y =0,(y+10) = 0, (y+2) = 0, (y-2) = 0
That is y = 0, y =-10, y =-2, y = 2
Which is your choice (c) 0, -10, 2, -2
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