Question

if a+b=2 and ab=-24 find the value of a^3-b^3​

Answer 1

Answer:

117

Step-by-step explanation:

Using the identity (a−b)

3=a

3−b 3

−3ab(a−b)

It is given that a−b=3 and ab=10, therefore,

(a−b)

3 =a 3−b 3−3ab(a−b)

⇒(3) 3 =a 3 −b 3

−(3×10)(3)

⇒27=a

3

−b

3

−(30×3)

⇒27=a

3

−b

3

−90

⇒a

3

−b

3

=27+90

⇒a

3

−b

3

=117

Hence, a

3 −b 3

=117.

Answer 2

Answer:

280

Step-by-step explanation:

first find the factor of -24

let take 6 × (-4)

put this value in both equation 1 and 2 where a = 6 and b= -4

equation 1 (a+b=2)

=6+(-4) [note: + will be change to - ]

=6-4

=2

equation 2 [a×b=(-24)]

= 6×(-4) [note: sign of - will be there in the answer]

= -24

now we have proof that a=6 and b= - 4 put the value this in a^3-b^3

= 6^3 - (-4^3)

= 216 - (-64) [note: - will change to + ]

= 216+64

= 280