Simple precalculas question please help you math gienuses ; )?

Question

find the x and y intercept of y = x^3 - 4x

the book give me this answer x=0 and x=2 and x= -2

Answer 1

The given equation is  y = x^3 - 4x

First find the x-intercept.

The x-intercept is the value of x, when y = 0.

0 = x^3 - 4x

 x^3 - 4x  = 0

x ( x^2 - 4) = 0

x = 0 and x^2 - 4 = 0

Write x^2 - 4 is (x + 2 )(x - 2)

x = 0 and (x + 2 )(x - 2) = 0

x = 0 , (x + 2 ) = 0 and (x - 2) = 0

x = 0 , x = - 2 and x = 2

The x - intercept are 0, - 2, 2

Next find the y-intercept.

The y-intercept is the value of y, when x = 0

y = (0)^3 - 4(0)

y = 0

The y - intercept is 0

x - intercept are 0, - 2, 2 and y - intercept is 0

 

 

Comments

thank you! could you please show the graph for the above equation.

Answer 2

 

i hope it helps a lil.

Comments

Thank you!!!

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nice graphical representation:)