* Formal: "¿Puede ayudarme con mi tarea?" (Can you help me with my homework?) This is the most polite and appropriate for addressing a teacher or a stranger.
* Informal: "¿Me ayudas con mi tarea?" (Will you help me with my homework?) This is suitable for friends and family.
* Informal and more pleading: "Ayúdame con mi tarea, por favor." (Help me with my homework, please.) This adds a stronger plea for assistance.
* Even more informal (and slightly whiny): "Necesito ayuda con mi tarea." (I need help with my homework.)
The best option depends on your audience and context.