Question

if 2x+1/3x=4 then prove that 27x^3+1/8x^3=189
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Answer 1

Answer:

  27x³ + 1/8x³ = 189

Step-by-step explanation:

We are given

            2x + 1 / 3x = 4

Multiplying by 3/2 on both sides we get

        ( 3 / 2 ) × ( 2x + 1 / 3x ) = 4 × ( 3 / 2 )

                            3x + 1 / 2x = 6

Taking cube on both sides we get

                      ( 3x + 1 / 2x )³ = 6³

Using formula (a + b)³ = a³ + b³ + 3ab(a+b) we get

        27x³ + 1/8x³ + 3×( 3x )×( 1/2x )×( 3x + 1 / 2x) = 216

Putting "3x + 1 / 2x = 6" we get

        27x³ + 1/8x³ + 3×3×(1/2 )×6 = 216

                 27x³ + 1/8x³ + 3×3×3 = 216

                       27x³ + 1/8x³ + 27 = 216

                               27x³ + 1/8x³ = 216 -27

                              27x³ + 1/8x³ = 189

Hence proved!

Answer 2

Answer:

If 2x+1/3x=4 then prove that 27x3+1/8x3=189