ANSWER
1.5(x)
EXPLANATION
The tree is originally x feet tall. If it grows 1/2 this height it means that now it is 1/2x taller, or we can express this as a decimal, 0.5x. If we add these two heights we'll have the new height of the tree:
[tex]x+0.5x=(1+0.5)x=1.5x[/tex]
