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show all algebraic work for full credit. 1) use the leading coefficient…

Question

show all algebraic work for full credit.

  1. use the leading coefficient and degree of the polynomial function ( f(x)=x^{3}-7 x^{2}+10 x ) to determine the end behavior of the graph. make sure to use the correct notation.
  2. the graph of a function, ( f ), is shown below. use the graph to estimate all turning points. circle all ( x )-values that are turning points of ( f ).
  3. multiply the following polynomials and write the answer in standard form.

( (x + 2 y)left(x^{2}-x y+3 y
ight) )

  1. multiple choice (one answer): select the graph of a polynomial function ( f(x) ) that satisfies the following clues:

( f(x) ) is positive on the intervals ( (-infty,-3),(-2,0) ), and ( (2,3) ).
( f(x) ) is negative on the intervals ( (-3,-2),(0,2) ), and ( (3, infty) ).
( f(x) ) is increasing on the intervals ( (-2.59,-1.03) ) and ( (1.03,2.59) ).
( f(x) ) is decreasing on the intervals ( (-infty,-2.59),(-1.03,1.03) ), and ( (2.59, infty) ).

Explanation:

1)

Step1: Identify the leading coefficient and degree

The polynomial function is \(f(x)=x^{3}-7x^{2}+10x\). The leading term is \(x^{3}\), so the leading coefficient \(a = 1\) (positive) and the degree \(n=3\) (odd).

Step2: Determine the end - behavior

For a polynomial function \(y = a x^{n}\) with \(a>0\) and \(n\) odd:
As \(x
ightarrow-\infty\), \(y = f(x)
ightarrow-\infty\) (since \(y=1\times(-\infty)^{3}=-\infty\))
As \(x
ightarrow+\infty\), \(y = f(x)
ightarrow+\infty\) (since \(y = 1\times(+\infty)^{3}=+\infty\))

A turning point of a function is a point where the function changes from increasing to decreasing or vice - versa.
Looking at the graph:

  • At \(x=-1.5\), the function changes from decreasing to increasing.
  • At \(x = 1.5\), the function changes from increasing to decreasing.

Step1: Use the distributive property (FOIL - like for polynomials with more than two terms)

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

Step2: Expand each part

\(x(x^{2}-xy + 3y)=x^{3}-x^{2}y+3xy\)
\(2y(x^{2}-xy + 3y)=2x^{2}y-2xy^{2}+6y^{2}\)

Step3: Combine like terms

\(x^{3}-x^{2}y + 3xy+2x^{2}y-2xy^{2}+6y^{2}=x^{3}+( - x^{2}y+2x^{2}y)-2xy^{2}+3xy + 6y^{2}=x^{3}+x^{2}y-2xy^{2}+3xy + 6y^{2}\)

Answer:

As \(x
ightarrow-\infty\), \(f(x)
ightarrow-\infty\); as \(x
ightarrow+\infty\), \(f(x)
ightarrow+\infty\)

2)