# Math Help - Limits with substitution

1. ## Limits with substitution

Okay, I just started AP Calc at school and I'm confused about how to determine limits by substitution and to support it graphically. I know this is probably really simple but I need help.

Problem: lim 3x^2(2x+1)
x approaches -1/2

Problem #2: lim e^x cos x
x approaches 0

2. Originally Posted by Jasmina8
Okay, I just started AP Calc at school and I'm confused about how to determine limits by substitution and to support it graphically. I know this is probably really simple but I need help.

Problem: lim 3x^2(2x+1)
x approaches -1/2

Problem #2: lim e^x cos x
x approaches 0

4. Is the first one supposed to be $3^{x^2(2x+1)}$ or $3x^{2}(2x+1)$?