.
Since the solution by @gosgarithmetic contains a lot of errors, giving the wrong answers and ,
I came to fix it.
Find my correct solution below.
And ignore that of @josgarithmetic, for your safety.
y =
Plug in the point coordinates
=
=
= 3*81 =
Using either original equations, .
Answer. y = .
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Regarding @josgarithmetic, this person is VERY well known (or better to say, very badly known, unfortunately) in this forum,
for his inability to solve problems correctly and to make calculations accurately.
So be very careful when you obtain "solutions" from him.
In half of all cases (if not at most cases) they are wrong.
Do not trust him and always wait for reaction of other tutors.
In the normal school environment he would be fired in the second day.
I think about thousands of visitors and students who do understand almost nothing in Math and who were misguided
by his false and wrong quasi- and pseudo-"solutions".
People, be careful about @josgarithmetic ! ! !