Solve using Matlab Single equations

So far I have:

L= 10*12; E= 30*10^6; I= 5; F=15000; a=4*12; b=L-a; x=sqrt((L^2-b^2)/3)

ymax=((F.*b.*x)/(6.*E.*I.*L)).*(L.^2-x.^2-b.^2)

ymax_v=0.75*ymax

>>results

x = 55.4256 ymax = 3.4054 ymax_v = 2.5540

location to the left (d) is supposed to equal approx. 31 and to the right(e) is supposed to equal 77. I am trying to solve it symbolic by using the solve function or fzero function using 24 and 120 as values close to x but I am not getting those answers.

A horizontal beam of length L is supported at each end ( 0 and x L), as shown in Fig. 11.21. Suppose an external vertical force F is applied to the beam at location a, where a is measured from the left end of the beam (from Fig. 11.21, note that a+ b L). Then the vertical deflection of the beam at some point x, x s a, is determined by the expression x=0 x=a Figure 11.21 - A horizontal beam with a point load 6EIL known as Young's modulus) where y is the vertical deflection, E is the modulus of elasticity (also known as Young's modulus), and lis the moment of inertia of the crosssectional area of the beam. (Note that E depends only on the beam material, and / depends only on the beam geometry.) suppose a 10-ft beam is made of steel (E = 30 x 106 psi), and the moment of inertia is 5 in4. If a vertical force of 15,000 lbf is applied at a 4 ft, determine (a) The maximum deflection, which occurs at x-V12-b2)/3