Trying to solve 4 equation with 4 unknowns

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.

[Liang Wei Teo]

you can try changing everything to matrix and solve it using Ax=b

[Yashas Kumar G B]

It's easier than all discription which can easily understood by students . By seeing that we can get general syntax of problem of such typee

[Tamara]

x + y + z + w = 10.3 2x - 7y + z - w = -1.5 -X - 3y - z + w = -6.9 3x + z - w = 2.4

Answer 1

[Walter Roberson]

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);

[omercan demirel]

it shows a: [1x1 sym]. Same for b c d too

[Walter Roberson]

Is that a problem? You asked for a symbolic solution and you received a symbolic solution. You can look at the individual solutions with, for example,

sol.a

[omercan demirel]

It worked. Thank you so much.

Also answers are: 5,6,4,8

Answer 2

[Liang Wei Teo]

you can try changing everything to matrix and solve it using Ax=b