MATLAB: Trying to solve 4 equation with 4 unknowns

Question

Hello,

I am trying to solve this problem:

2a + 1b + 0c + 6d = 64
5a + 2b + 0c + 0d = 37
0a + 7b + 2c + 2d = 66
0a + 0b + 8c + 9d = 104

So I wrote this code:

clear;
clc;
equation1=64-2*a-b-6*d;
equation2=37-5*a-2*b;
equation3=66-7*b-2*c-2*d;
equation4=104-8*c-9*d;
sol=solve(equation1,equation2,equation3,equation4);

But it gives Undefined function or variable 'a' in line 3. I know I am missing something very obvious but I cannot find it. Could you help me?

Thank you.

Answer 1

syms a b c d
equation1=64-2*a-b-6*d;
equation2=37-5*a-2*b;
equation3=66-7*b-2*c-2*d;
equation4=104-8*c-9*d;
sol=solve(equation1,equation2,equation3,equation4);