Question

4. The difference between two positive numbers is 7 and the difference between thes
cubes is 805. If 'A' represents their product and 'B' represents the sum of their squares,
find the value of 'A-B'.



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Answer 1

Answer:

Given :-

The  difference between two positive numbers is 7 and the difference between these  cubes is 805. If 'A' represents their product and 'B' represents the sum of their squares,

To Find :-

A - B

Solution :-

So,

Let the number be n and m

A = n × m = nm

B = n² + m² = (n + m)²

Now

n³ - m³ = 805

(n - m) (n² + m² + nm) = 805

Since difference is 7

7 × n² + m² + nm = 805

n² + m² + nm = 805/7

n² + m² + nm = 115

(n² + n) + (m² + m) = 115

A + B = 115

Now

On squaring the first eq.

(n - m)² = (7)²

(n - m)² = 49

B - 2A = 49

Now

A + B - B + 2A = 115 - 49

A + 2A = 66

3A = 66

A = 66/3

A = 22

By using 2

B - 2(22) = 49

B - 44 = 49

B = 49 + 44

B = 93

A - B = 22 - 93 = -71