Question 185101
Finding all real zeros means that we are finding all possible values for x that will satisfy the equation and still are in the "real number system".

If we have the function {{{f(x)=x^5+x^3-6x}}} we are looking for all of the x-intercepts, which are the same as roots/zeros. The best way to find these algebraically is to factor it out. In this function there is an x we can factor out from the beginning.

{{{y = x*(x^4+x^2-6)}}}

Now we are looking for 2 numbers that add up to be 1, and multiply to be -6. The two numbers I came up with are -2 and 3. Let's factor this out using the reverse FOIL method and these numbers.

{{{y = x*(x^2+3)*(x^2-2)}}}

Since we are finding the zeros, which are essentially roots/x-intercepts, we can set y = 0 because the x-intercept will have a y coordinate of 0. We now have this equation:

{{{0 = x*(x^2+3)*(x^2-2)}}}

Now by the zero factor theorem, if the product is 0, than we can set each factor to 0.

{{{x = 0}}}
{{{x^2+3 = 0}}}
{{{x^2-2 = 0}}}

Now we solve for x in each of these.

{{{x = 0}}} Solved.
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{{{x^2+3 = 0}}}
{{{x^2 = -3}}}
{{{x = sqrt(-3)}}} 2 Answers.
{{{x = -sqrt(-3)}}} Solved.
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{{{x^2-2 = 0}}}
{{{x^2 = 2}}}
{{{x = sqrt(2)}}} 2 Answers.
{{{x = -sqrt(2)}}} Solved.

The first equation is already solved, we already have 1 real root. The second equation can't be done in the real number system since we cannot take the square root of a negative number without using the imaginary number system. The third equation has two possible values, both of which are real and satisfy the equation.
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In the original equation we had {{{x^5}}}. Since it is raised to the 5th power, there are 5 total solutions, and we have found 3 of them to be real zeroes. The other two are imaginary numbers (from case 2). So our answer would be:

{{{x = 0}}}
{{{x = sqrt(2)}}} Note that these numbers are irrational, but still real.
{{{x = -sqrt(2)}}} This is because they represent a decimal, that is between two numbers.
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For your second question, we need to graph it and describe the graph. So the equation would look like this:
{{{g(x)=-x^2+10x-16}}}
{{{ graph( 330, 300, -1, 10, -10, 10, -x^2+10x-16) }}}
We can see that the graph opens down. Since it is a parabola, it starts going up, but it hits a vertex at (5,9) and then starts to go down.