SOLUTION: The function of f(x) = 3x^2+9x-3 has x-intercepts as p and q. So what is the value of p-pq+q?

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Question 1180171: The function of f(x) = 3x^2+9x-3 has x-intercepts as p and q. So what is the value of p-pq+q?
Found 2 solutions by ikleyn, greenestamps:
Answer by ikleyn(52765) About Me  (Show Source):
You can put this solution on YOUR website!
.

According to the Vieta's theorem,


    p + q = -9/3 = -3   and   pq = -3/3 = -1.


Therefore,   p - pq + q = -3 - (-1) = -3 + 1 = -2.      ANSWER

Solved.

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Notice, that in this problem, you do not need to solve equation and to find its roots.

Using the Vieta's theorem, you can answer the problem's question without doing this boring work.



Answer by greenestamps(13198) About Me  (Show Source):
You can put this solution on YOUR website!


For the quadratic equation

y=ax%5E2%2Bbx%2Bc

the sum of the roots is -b/a and the product of the roots is c/a.

You have

y=3x%5E2%2B9x-3

with roots p and q.

p%2Bq=-9%2F3=-3
pq=-3%2F3=-1

p-pq%2Bq=%28p%2Bq%29-pq=-3-%28-1%29=-2

ANSWER: -2