document.write( "Question 1044241: I am not understanding these at all. Can someone help me with this example?\r
\n" ); document.write( "\n" ); document.write( "Given the quadratic function f(x) = 3x2 + 6x - 4
\n" ); document.write( "a. Find the vertex
\n" ); document.write( "b. Find the axis of symmetry
\n" ); document.write( "c. Find the x- and y-intercepts
\n" ); document.write( "d. State the domain and range of the function
\n" ); document.write( "e. Find the interval(s) over which the function is increasing
\n" ); document.write( "f. Find the interval(s) over which the function is decreasing
\n" ); document.write( "g. Graph the function
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #659517 by rothauserc(4718)\"\" \"About 
You can put this solution on YOUR website!
f(x) = 3x^2 +6x - 4
\n" ); document.write( ":
\n" ); document.write( "This is a parabola that curves upward, here is its graph
\n" ); document.write( ":
\n" ); document.write( "\"+graph%28+300%2C+200%2C+-2.8%2C+0.8%2C+-8%2C+4%2C+3x%5E2+%2B6x+-4%29+\"
\n" ); document.write( ":
\n" ); document.write( "The general form of a polynomial for the given function is
\n" ); document.write( ":
\n" ); document.write( "f(x) = ax^2 +bx +c, where a, b, c are real numbers
\n" ); document.write( ":
\n" ); document.write( "The x coordinate for the vertex is given by
\n" ); document.write( ":
\n" ); document.write( "x = -b /2a, for our given function we have
\n" ); document.write( ":
\n" ); document.write( "x = -6 / (2 * 3) = -1
\n" ); document.write( ":
\n" ); document.write( "substitute for x in the given function for the y coordinate of the vertex
\n" ); document.write( ":
\n" ); document.write( "y = f(x) = 3(-1)^2 +6(-1) -4 = -7
\n" ); document.write( ":
\n" ); document.write( "***************************************
\n" ); document.write( "a) vertex is at (-1, -7)
\n" ); document.write( "***************************************
\n" ); document.write( ":
\n" ); document.write( "***************************************
\n" ); document.write( "b) axis of symmetry is x = -1
\n" ); document.write( "half of the parabola is to the left and half of the parabola is to the right
\n" ); document.write( "***************************************
\n" ); document.write( ":
\n" ); document.write( "The y intercept is found by setting x = 0 and solve for y
\n" ); document.write( "y = 3(0)^2 +6(0) -4 = -4
\n" ); document.write( ":
\n" ); document.write( "x intercept/s are found by solving the given function for x, when f(x) = 0
\n" ); document.write( ":
\n" ); document.write( "3x^2 +6x -4 = 0
\n" ); document.write( ":
\n" ); document.write( "use quadratic formula to solve for x
\n" ); document.write( ":
\n" ); document.write( "x = (-6 + square root((-6)^2 -4*3*(-4))) / (2(3)) = (-3 + square root(21)) / 3
\n" ); document.write( ":
\n" ); document.write( "x = (-6 - square root((-6)^2 -4*3*(-4))) / (2(3)) = (-3 - square root(21)) / 3
\n" ); document.write( ":
\n" ); document.write( "*****************************************************************************
\n" ); document.write( "c) y intercept is -4
\n" ); document.write( "x intercepts are (-3 + square root(21)) /3, (-3 - square root(21)) / 3
\n" ); document.write( "note the intercepts are where the graph of f(x) crosses the y axis(y intercept) and where f(x) crosses the x axis (x intercepts
\n" ); document.write( "******************************************************************************
\n" ); document.write( ":
\n" ); document.write( "*************************************************
\n" ); document.write( "d) The domain and range of f(x) are the real numbers
\n" ); document.write( "*************************************************
\n" ); document.write( ":
\n" ); document.write( "***************************************************
\n" ); document.write( "e) The graph of f(x) shows us the f(x) is increasing on the interval [-1, +infinity) and f(x) is decreasing on the interval [-infinity, -1]
\n" ); document.write( "****************************************************
\n" ); document.write( ":
\n" ); document.write( "*****************************************************
\n" ); document.write( "f) see graph above
\n" ); document.write( "*****************************************************
\n" ); document.write( ":
\n" ); document.write( "
\n" ); document.write( "
\n" );