Do you think Macbeth would have killed Duncan if his wife had not urged him to do so?Cite evidence from the first two acts to support your opinion.

I think it just depends on how you read the text. I could make an argument to you either way. And I will.

Firstly, I think Macbeth shows real wavering doubts about doing the murder. He says, just after he receives the news that he's just going to leave it up to the fates, and let what happens happen:

If chance will have me king, why, chance may crown me
Without my stir. Come what come may,
Time and the hour runs through the roughest day.

So that's evidence that he's not going to do it. And then later in Act 1, Scene 7, he talks himself right out of it, even telling Lady M

We will proceed no further in this business:
He hath honor'd me of late, and I have bought
Golden opinions from all sorts of people,
Which would be worn now in their newest gloss,
Not cast aside so soon.

She persuades him around. But before that, it looks very much like he isn't going to do it. And why would he? If the prophecies are true, they'd happen no matter what he did.

On the other hand, Macbeth admits very quickly after the prophecies that he has "black and deep desires" for the throne, for power, and to become king. It's clearly been going on long before the prophecies were made by the witches:

Stars, hide your fires;
Let not light see my black and deep desires:
The eye wink at the hand; yet let that be
Which the eye fears, when it is done, to see.

Macbeth is undoubtedly ambitious. And, in the end, he does the deed and murders Duncan. Surely he wouldn't murder someone simply because his wife said so? Or would he?

It's one of those questions. You can't imagine him without his wife, really - you can't imagine what he'd be like. So you can argue it both ways.

Hope it helps!