After solving I have come up with 6 2/9 or 6.22222.
At heart we're being asked for a line through two points,

In general the line through (a,b) and (c,d) is

Check that you understand why both (a,b) and (c,d) are on this line.
Here our indepedent variable, instead of x, is T, temperature. Our dependent variable is v, velocity. Substituting,





That's our answer; let's check it.
When T=40, v = (5/9)40 + (2995/9) = 355 good
When T=49, v= (5/9)49 + (2995/9) = 360 good
3m - 5p = 12
3m(-3m) -5p = (-3m)+ 12
-5p = -3m + 12
(-5)/-5p = (-5)/ (-3m + 12)
p = 3/5m + 12/-5
Answer:
the linearization is y = 1/4x +5/4
the linearization will produce <em>overestimates</em>
the values computed from this linearization are ...
f(3.98) ≈ 2.245
f(4.05) ≈ 2.2625
Step-by-step explanation:
Apparently, you have ...

from which you have correctly determined that ...

so that f(3) = 2 and f'(3) = 1/4. Putting these values into the point-slope form of the equation of a line, we get the linearization ...
g(x) = (1/4)(x -3) +2
g(x) = (1/4)x +5/4
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The values from this linearization will be overestimates, as the curve f(x) is concave downward everywhere. The tangent (linearization) is necessarily above the curve everywhere.
__
At the given values, we find ...
g(3.98) = 2.245
g(4.05) = 2.2625