If 3x+2y=20 and xy=14/9 then find 27x^3+8y^3

by

If 3x+2y=20 and xy=14/9 then find 27x^3+8y^3 [S.Chand ICSE Class 9 Chapter 3 Exercise 3.1 Expansion and Factorisation Solution ]

Given That, 3x+2y=20 and xy=$\frac{14}{9}$

3x+2y=20

∴ (3x+2y)3=(20)3

⟹ (3x)3 + (2y)3 +3.3x.2y(3x+2y) = 8000

⟹ 27x3+8y3+18xy(20) = 8000

⟹ 27x3 +8y3 +18 x $\frac{14}{9}$ x 20 =8000

⟹ 27x3 +8y3 +560 = 8000

⟹ 27x3 +8y3 = 8000 -560

⟹27x3 +8y3 = 7440

∴ 27x3+8y3 = 7400 [Ans]

See More

  1. If (x+1/x)^2=3 then show that x^3+1/x^3=0
  2. If x^2+1/25x^2 =8 3/5 find the value of x^3+1/125x^3
  3. If a^2-5a+1=0 find the value of a+1/a and a^2+1/a^2
  4. If (x+1/x)=2 then find (x^2+1/x^2) ,(x^3+1/x^3) and (x^4+1/x^4)
  5. If x+$\frac{1}{x}$=$\sqrt{3}$ then find $x^3 + \frac{1}{x^3}$
error: Content is protected !!