Which statement best describes the graph of x3 - 3x2 - x + 3?
It starts down on the left and goes up on the right and intersects the x-axis at x = -1, 2, and 3.
It starts down on the left and goes up on the right and intersects the x-axis at x = -1, 1, and 3.
It starts up on the left and goes down on the right and intersects the x-axis at x = -1, 2, and 3.
It starts up on the left and goes down on the right and intersects the x-axis at x = -1, 1, and 3.
Solution:
Given expression x3 - 3x2 - x + 3
Let y = x3 - 3x2 - x + 3
In order to find the nature of the graph, we need to plot the graph
To get graph, take sample points for (x, y) and plot them on X-Y axis.
In order to know where the graph intersects x-axis, we need to put y = 0
y= x3 - 3x2 - x + 3 = 0
The sum of all coefficients of given cubic equation: x3 - 3x2 - x + 3 = 0 is zero
Hence x = 1 is a root of given cubic equation i.e. (x - 1) is a factor of x3 - 3x2 - x + 3
Now, cubic algebraic polynomial:
x3 - 3x2 - x + 3 can be factorized as follows
= x3 - 3x2 - x + 3
= x2(x - 1) - 2x(x - 1) - 3(x - 1)
= (x - 1)(x2 - 2x - 3)
= (x - 1)(x2 - 3x + x - 3)
= (x - 1)(x(x - 3) + (x - 3))
= (x - 1)(x - 3)(x + 1)
Hence, the solution of given cubic equation will be given as (x - 1)(x - 3)(x + 1) = 0, x = -1, 1, 3
Therefore, the graph intersects x-axis at x = -1, 1, 3
It starts down on the left and goes up on the right and intersects the x-axis at x = -1, 1, and 3.
Which statement best describes the graph of x3 - 3x2 - x + 3?
Summary:
For expression x3 - 3x2 - x + 3, the graph starts down on the left and goes up on the right and intersects the x-axis at x = -1, 1, and 3.
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