Question

Evaluate the following limits: `lim_(y -> 1/2)[(1 - 8y^3)/(y - 4y^3)]`

Answer 1

`lim_(y -> 1/2)[(1 - 8y^3)/(y - 4y^3)]`

= `lim_(y -> 1/2) (1 - 8y^3)/(y(1 - 4y^2)`

= `lim_(y -> 1/2)((1)^3 - (2y)^3)/(y[(1)^2 - (2y)^2]`

= `lim_(y -> 1/2) ((1 - 2y)(1 + 2y + 4y^2))/(y(1 - 2y)(1 + 2y)`

= `lim_(y -> 1/2) (1 + 2y + 4y^2)/(y(1 + 2y)) ....[(because y -> 1/2 "," therefore y ≠ 1/2),(therefore 2y ≠ 1 therefore 2y - 1 ≠ 0),(therefore 1 - 2y ≠0)]`

= `(1 + 2(1/2) + 4(1/2)^2)/(1/2[1 + 2(1/2)]`

= `(1 + 1 + 1)/((1)/(2)(2)`

= 3