Question

if the sum and the product of two numbers are 7 and 45/ 4 respectively, the sum of their cubes.​

Answer 1

Answer:

let the numbers be a and b

Step-by-step explanation:

A.T.Q , it is given that

a+b=7

a × b=45/4

from equation 1 we get

a=7-b

now put this value in equation number 2

(7 - b) b= 45/4

7b - b²= 45/4

y²- 7b + 45/4=0

4y²-28b+45=0

4b²-18b-10b+45=0

2b(2b-9) -5(2b-9) =0

(2b-9) (2b-5) =0

b=9/2, b=5/2

put y=9/2 in any equation we get

a=5/2

sum of cubes=(5/2) ³+(9/2) ³

=125/8+729/8

=854/8

=427/4

hence the value of their cube is 427/4

thank you