because he just knows
i think Macbeth wanted to be king. he couldn't though because king Duncan was. So Macbeth killed him. Then Banqou was suppose to be next to be kind, i believe. So he hired the revengers or avengers to murder him. Next was fleance. i don't know what happened to him.
Banquo probably doen't know for sure about how Macbeth is planning on killing Duncan so he can become king. Even if Banquo did know, he is a very loyal friend to Macbeth and will keep all of his suspicions to himself. Which is ironic, because Mabeth ends up hiring murderers to kill Banquo, which goes to show you that Macbeth really isn't that loyal.
Well there is a theory that actually Macbeth was there when Banquo was killed, and Macbeth was actually the third murderer. (Kind of unlikely since the other two murderers know Macbeth and would have recognized him) Also if you don't accept this theory, Macbeth might have not killed Banquo with his own hands because by that time he was already king, and he had the finance and the oppurtunity to hire murderers. As Macbeth himself says in Act 3 scene one from line 125, he does have the power to openly have Banquo destroyed, "yet I must not, for certain friends that are both his and mine, whose loves I may not drop, but wail his fall who I myself strike down." Yet this is just an excuse, a lie because Macbeth knows that there is no good reason for Banquo and Fleance to be killed and so he could not have him openly accused of anything. Macbeth knows that Banquo and Fleance are innocent. He orders their murder out of fear that the throne will be taken away from him and that Banquo's decendants will inherit it.
*Banquo. Macbeth's best friend is Banquo, but he is also Macbeth's enemy. After the meeting with the witches, Macbeth finds out that he will become the Thane of Cawdor and the King of Scotland. Eventually, he achieves both of these prophecies. Banquo, Macbeth, and Lady Macbeth are the only people that know about the witches. Banquo becomes suspicious of Macbeth because Macbeth fulfills the prophecy after King Duncan is murdered, and Macbeth acknowledges this fact. Basically, Macbeth doesn't trust Banquo.
Macbeth wants Banquo dead because Banquo witnessed what the three witches said. The three witches stated that Macbeth would one day become king. Now that Macbeth has become king, and done so by taking the life of the previous King Duncan, he fears that Banquo will spread the word that Macbeth was the one to commit the murder.
Technically Macbeth only murdered Duncan in the begining and young siward at the end. Then he had the murderers go to kill Fleance and his father. Fleance escaped so he wouldn't count, and Macbeth also had the murders go to kill the Thane of Fife (macduff) and ends up only having the family killed. Macbeths wife in the end dies of what no one really knows but it can be argued that he was the cause of her death. He also slays young siward before macduff challenges him. So it really depends on how you look at it. If you want to know how many he killed with his own hands then 2.
Lady Macbeth drugs the guards stationed outside King Duncan's chamber to ensure they are unconscious and unable to interfere with her plan to frame them for Duncan's murder. This allows Macbeth to easily access Duncan's chamber and carry out the assassination.
Macbeth doesn't really have a conflict with them. Banquo suspects Macbeth of killing Duncan, but isn't saying anything. Macbeth is annoyed by the witches' prediction that his children will not succeed him (Does he have children? The way things are going between him and his wife, is it likely that he will?) but that Banquo's decendants will. He is jealous. Macbeth's murder of Banquo and attempt on Fleance's life are an attempt to prove to himself that his future is not controlled, and that he is free. He wants to know that he became king because of what he did, not some inexorable fate. When the murderers fail to kill Fleance, he says, "Then comes my fit again!". He has not proven that he is free. The witches' predictions about Banquo can come true. Maybe it is all a matter of fate after all.
One example of dramatic irony in Act 3 of Macbeth is when Macbeth decides to have Banquo and Fleance killed in order to secure his throne, without knowing that Fleance will escape. Another example is when Macbeth expresses concerns about not being able to enjoy his newfound power, unknowingly foreshadowing his descent into paranoia and guilt.
He thought he heard a voice say "Sleep no more"
Banquo is killed but his son, Fleance, escapes :)
That is a step On which I must fall down, or else o'erleap, For in my ways it lies. APEX