Hello, harshal54321!
You really should learn to use parentheses.
Don't make us guess at what you mean . . .
. . . . 23x³ + 45
. lim -------------
x→∞ .78x³ + 9
Divide top and bottom by x³
. . . . 23 + 45/x³ . . . .23 + 0 . . . . 23
. lim .------------ . = . --------- . = . ---
x→∞ .78 + 9/x³ . . . . 78 + 0 . . . . 78