Error : Subscript indices must either be real positive integers or logicals.

Trying to use fzero to solve for the equation, want to first plot the function.. but i keep getting this error

"Subscript indices must either be real positive integers or logicals."

g1 = 1.4;

R1 = 287;

T = 283.15;

g4 = 1.667;

R2 = 2077;

a1 = sqrt(g1*R1*T);

a4 = sqrt(g4*R2*T);

ar = a1/a4;

z = -5;

x = linspace(3,4,100);

F = (8/(1-((g4-1)*ar*(x-1))/sqrt(2*g1(2*g1+(g1+1)*(x-1))))^z)-8;

figure(1)

plot(F,x);

Answer 1

[JESUS DAVID ARIZA ROYETH]

you missed a "*" here : 2*g1*(2*..... and many "." ./

g1 = 1.4;
R1 = 287;
T = 283.15;
g4 = 1.667;
R2 = 2077;
a1 = sqrt(g1*R1*T);
a4 = sqrt(g4*R2*T);
ar = a1/a4;
z = -5;
x = linspace(3,4,100);
F = (8./(1-((g4-1)*ar*(x-1))./sqrt(2*g1*(2*g1+(g1+1).*(x-1)))).^z)-8;
figure(1)
plot(F,x);