Question 1179791
.If the area (in square units) of the region under the curve of the function f(x) = 3x − 1 
on the interval [a, 4], where a < 4, is 12 square units, identify all the possible values of a. what values are correct?
a. -3
b. 0
c. -16/5
d. 8/3
e. -2
f. 7/2
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In the post by @CPhill, his solution has fatal errors and leads to wrong answer.



<pre>
In section (3) of his solution, he correctly derived an equation for 'a'  3a^2 - 2a - 16 = 0,

but in section (4), he incorrectly factored it as (3a+8)*(a-2) = 0,

obtaining wrong solutions a = -8/3 and  a = 2.



Actually, the correct factoring is (3a-8)*(a+2) = 0, giving  a = 8/3  or  a = -2.



Then the further analysis leads to the answer  (d):  a = 8/3.
</pre>