Matlab model using normal equations

(See attached file for full problem description)

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This model is used to analyze the body's response to a bolus injection of this antibiotic:
B(t) = B0e(-k*t)
Using this model, and data provided for the average plasma concentration data in ug/ml with time in hours :
a) perform linear regression on this penicillin clearance using the normal equations
b) plot the concentration data and re-plot the log of the concentration data to show that it appears linear.
c) Determine initial concentration, B0, and elimination rate constant, k

Concentration (ug/ml) Time (min)
89 22
60 44
30 88
15 132
7 176

a) for linear regression
ln( B ) = ln( B0 )- Kt

I'm not sure how to use the normal equations in MATLAB to plot this? We're not supposed to use polyfit function… I think you have to make a 2 column matrix with a column of 1's and a column of the time?
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(See attached file for full problem description)