Question

if a-b = 2, ab = 15, find: i) a+b ii) a^3 - b^3​

Answer 1

Step-by-step explanation:

i) a = 5

b = 3

Hence, 5+3 = 8.

ii)

$= {a}^{3} - {b}^{3}$

$= {5}^{3} - {3}^{3}$

$= 125 - 27$

$= 98$

Hope it helps you..!

Answer 2

Answer & step by step instructions:

(a+b)²=(a-b)²+4ab=4+4×15=64

(a+b)=√64=8

[As we know,(a+b)²=(a-b)²+4ab]

a³-b³=(a-b)³+3ab(a-b)

=2³+3×15×2

=8+90=98

This is your answer.

→(a+b)=8

→a³-b³=98