Question

If a+b =7 and ab =12 find the value of a3+b3

Answer 1

Answer:

91

Step-by-step explanation:

• $(a+b)^{3} = a^{3} + b^{3} + 3a^{2} b + 3ab^{2}$

$a^{3} + b^{3} \\\\= (a+b)^{3} - 3a^{2} b - 3ab^{2}\\\\= (a+b)^{3} - 3ab(a+b)\\\\= 7^{3} - 3.12.7 = 343 - 252 = 91$