*Please help me.You have to factor by completing.
Let's look at #1:
3x^2 + 17x + 10
We have 2 and 5 as factors of the last term.
What combinations can we do to arrive at the middle term?
(3x + ?)(x + ?)
Let's try (3x + 5)(x + 2), which will be 3x^2 + 11x + 10. This is not what we want.
Let's try (3x + 2)(x + 5), which will be 3x^2 + 17x + 10. This IS what we want; therefore, we have found the factors of this trinomial.
Here's a few hints for the other two.
Hint for #2: First factor out 5. Then factor what's left.
Hint for #3: First factor (a - 5b). Can you determine the second factor?
I hope this will help.