Search 83,491 tutors
FIND TUTORS
Ask a question
0 0

solve using substitution 2y=x^2 and y=4x^3

Tutors, please sign in to answer this question.

1 Answer

Alex:
 
First equation gives y = x2 / 2.  So x2 / 2 = 4 x3, giving x = 1 / 8 and y = x2 / 2 = 1/128. 
 
Check y = 4x3 = 4(1/512)= 1/ 128, 2y = 1/64 and x2 = (1/8)2 = 1/64.
 
Dattaprabhakar (Dr.G.)

Comments

I can't figure out how to get the x = 1/8 
 
I know how to get x2/2 = 4x3 but I don't understand how that becomes 1/8
 
Thank you for the help!
x2 / 2 = 4 x3.
 
Divide both sides by x.  (Note that x = 0 is a solution but not interesting.  So look for non-zero solutions.   Then you can divide by x on both sides.)
 
You get 1 / 2 = 4 x.
 
Divide both sides by 4.
 
You get 1 / 8 = x.  This is the same as x = 1 / 8.  Do you follow?
 
Dattaprabhakar (Dr. G.)