Question

find the value of a³+b³, when a-b=5 and ab=-2​

Answer 1

Answer:

115

Step-by-step explanation:

a-b=5

(a-b)²=25

a²+b²-2ab=25

a²+b²=25+(2)(-2)

a²+b²=25-4=21

a³-b³=(a-b)(a²-ab+b²)=(5)(21+2)=5×23=115

Answer 2

Answer:

a³+b³=125

Step-by-step explanation:

a^3+b^3=>(a-b) (a^2 -ab +b^2)

=> 5(a^2-(-2) +b^2)

=>5(a²+b²+4)

=>5[(a-b) ²+2ab+4]

=>5(5) ²+2(-2) +4

a³+b³ =>125.