1)
(a+b)²=a²+2ab+b²
(5y+4)²
a=5y
b=4
Therefore:
(5y+4)²=(5y)²+2(5y)(4)+(4)²=25y²+40y+16
Answer: (5y+4)²=25y²+40y+16
2)
(a+b)³=a³+3a²b+3ab²+b³
(5y+4)³
a=5y
b=4
therefore:
(5y+4)³=(5y)³+3(5y)²(4)+3(5y)(4)²+(4)³=125y³+60y²+240y+64
Answer: (5y+4)³=125y³+60y²+240y+64
