Algebra Question

Here, h is the height of the tree.

from the Pythagorean theorem:

h² + 80² = (11 + 2h)²

h² + 6400 = (11 + 2h)(11 + 2h)

h² + 6400 = 121 + 44h + 4h²            Subtract h² and 6400 from both sides.

0 = -6279 + 44h + 3h²                      Rearrange.

0 = 3h² + 44h - 6279                        Use quadratic formula to solve for h.

$h = {-44 \pm \sqrt{44^2-4(3)(-6279)} \over 2(3)} \\~\\ h = \frac{-44\pm278}{6} \\~\\ h=\frac{-44+278}{6}=39 \qquad\text{or}\qquad h=\frac{-44-278}{6}=-\frac{161}3$

So...the height of the tree must be 39 feet

Let the tree height  = h

And we have a rigrt triangle such that :

h^2  +  80^2   =  (2h + 11)^2     simplify

h^2  +  6400  =  4h^2 + 44h + 121

3h^2 + 44h  - 6279  = 0    

Solving this  using  the  quadratic formula and taking the positive answer  we get that h =39 ft