4x-5z=16 xz=12 64x^3-125z^3=?

• sorry, result will be 15616 not -7424, solve the above expression by putting the given value u'll get it.
• 10 years agoHelpfull: Yes(2) No(2)
• (4x)^3-(5z)^3 can be written as (4x-5z)^3+60xz(4x-5z) and solve it using the given information
  the result will be -7424
• 10 years agoHelpfull: Yes(1) No(3)
• Ans:- 3520
  
  Solution:-
  
  4x-5z=16
  xz=12
  64x^3-125z^3=?
  
  (4x)^3-(5z)^3=?
  
  Formula
  a^3-b^3 = (a-b)(a^2-ab+b^2)
  a^2+b^2 = (a+b)^2-2ab
  
  Then,
  
  (4x)^3-(5z)^3 = (4x-5z)((4x)^2-(4x)(5z)+(5z)^2)
  = 16*((4x-5z)^2-3(4x)(5z))
  = 16*(256-36)
  = 3520
• 10 years agoHelpfull: Yes(1) No(3)
• ans is 3520
  let a-b=4x-5z=12,, ab=xz=12
  (a-b)^3=a3-b3-3a^2b+3ab^2
  so a^3-b^3==(a-b)^3-3ab(a)+3ab(b)
  a^3-b^3=(a-b)^3-3ab(a-b)
  substitute values
  ===>16^3-3*12(16)
  ====>3520
• 10 years agoHelpfull: Yes(1) No(0)
• no,answer will be 15616, by applying formula a^3-b^3=(a-b)^3-3*a*b(a-b)
• 10 years agoHelpfull: Yes(0) No(1)