Question

if a+b=9 and ab=20 find the value
اعتماد​

Answer 1

Answer:

a3+b3=189

Step-by-step explanation:

We have (a+b)3=a3+b3+3ab(a+b)

∴a3+b3=(a+b)3−3ab(a+b)

=(9)3−3×20(9)

=729−540=189

∴a3+b3=189