Question

the sum of two numbers is 7 and the sum of their cubes is 133 find the sum of their square
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Answer 1

Answer:

29

Step-by-step explanation:

let the numbers are x and y

ATQ,

x+y=7 and,

x^3+y^3=133

or, (x+y)^3-3xy(x+y)=133

or, 7^3-3xy × 7=133 ( since,x+y=7)

or, 343-21xy=133

or, 343-133=21xy

or, 210=21xy

or, xy=10

Now,

x^2+y^2=(x+y)^2-2xy

=7^2-2×10

=49-20

=29