Question

e) If x-y=4 and xy=21, find x³-y³​

Answer 1

Step-by-step explanation:

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Answer 2

Answer:

Here you go ..............

Step-by-step explanation:

Given that, x-y = 4

xy = 21

we know that (x+y)² - (x-y)² = 4xy

(x+y)² - 4² = 4(21)

(x+y)²-16 = 84

(x+y)² = 100

x+y = 10 ..... Equation (1)

x -y = 4 ...... Equation (2)

On solving the equations we get x = 7 and y = 3

x³ - y³ = 7³ - 3³ = 343 - 27 = 316

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