Question

Q2. If 2x +3y = 13 and xy = 6, find the value of 8x3 + 27y3.

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Answer 1

Answer:

hope it will help you

Step-by-step explanation:

2x + 3y = 13

Cubing on both sides

(2x +3y )³= 13³

(2x)³ + (3y)³ + 3.2x.3y ( 2x +3y) = 2197

8x³+27y³ + 18xy (13) = 2197

8x³ + 27y³ + 18×6(13) = 2196

8x³ + 27y³ +1404 =2196

8x³ + 27y³ = 2196-1404

8x³ + 27y³ = 792

therefore, 8x³+27y³ = 729

Answer 2

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Given :-

2x + 3y = 13

& xy = 6

Have To Find Out :-

Value of (8x³ + 27y³)

Using Formula :-

(a + b)³ = a³ + b³ + 3ab(a + b)

Explanation :-

From Giving equation -

2x + 3y = 13

Doing Cube Both Sides

(2x)³ + (3y)³ + 3(2x)(3y)(2x + 3y) = 2197

8x³ + 27y³ + 18xy(2x + 3y) = 2197

8x³ + 27y³ + 18(6)(13) = 2197

8x³ + 27y³ = 2197 - 234*6

= 2197 - 1404

= 793

Result :-

(8x³ + 27y³) = 793