factor the trinomial by grouping
posted by Adriana on .
15x^39x^26x
Can someone please show me how to factor completely.. trying to learn how to do factoring

Usually factoring by grouping is useful when patterns jump out at you:
x^3 + 3x^2  6x  18
you can see x(x^26) + 3(x^26)
In your problem, that's not likely, so grouping is not a useful method. Instead, factor out the 3x to get
3x(5x^2  3x  2)
Now, if you want to use grouping, you have to play around a bit:
5x^23x2 = 5x^25x + 2x2
= 5x(x1) + 2(x1)
= (5x+2)(x1)
Again, picking up on how to group is a skill learned through experience. Just buckle down and do a few hundred exercises, and you too will be proficient!