Question

FInd the zeros of the function using Fundamental Theorem of Algebra, the Rational Root Theorem, Descartes' Rule of Signs, and the Factor Theorem.

x^2 - 7x - 72
Please try your best to explain how you do this or just show your work, it will help me with the rest of the problems.

Answer 1

that function has not rational zeros

Answer 2

That's what I came up with too, what about complex zeros though?

Answer 3

no

Answer 4

the zeros are real

Answer 5

the problem says there can be complex zeros, i just have trouble finding them

Answer 6

the zeros r real just use a calculator or the quadratic formual and u will see

Answer 7

What i had to do for this assignment, is take a rectangular box, measure the lwh and find the volume:
l:7 w:4 h:3 V:84
Then I had to rewrite the equation as if I were solving for length, with the volume plugged in:
84 = (4)(3)x

Answer 8

84 = 12x
Then I had to rewrite the equation expressing the width and height of the object in terms of x plus or minus a constant. For example, if the height measurement is 4 inches longer than the length, then the expression for the height will be (x + 4), and I got:
84 = (x - 3)(x - 4)
Then I had to write in standard form:
84 = x^2 - 4x - 3x +12
84 = x^2 - 7x + 12
0 = x^2 - 7x - 72
And then I had to write it as a function (f(x)):
f(x) = x^2 - 7x - 72
Now I'm stuck trying to finish this, by finding the zeros of the function!

Answer 9

You missed out an x there. The equation should have been : 84 = (x-3)(x-4) x . not just (x-3)(x-4) . correct that and try again.

Answer 10

Oh wow! Thanks for that, I'll try again! And sorry about the mistake both of you!

Answer 11

You started with a real world object so you should have real numbers only as your answer.

Answer 12

okay, thanks!

Answer 13

I should get this once that was simplified?
0 = x^3 - 7x^2 + 12 - 84