Question

find the expansion of (7 - y)^3

Answer 1

formula =a^3 - b^3 - 3(ab) ( a-b)

SOLUTION

= 7^3 - y^3 - 3( 7 )( y ) ( 7 - y )

= 343 - y^3 - ( 21y ) ( 7-y)

= 343 - y^3 - 141y - 21y^2

⇒ y^3 + 21y^2 + 141y - 343 = 0

hope it helps