Question

Why during finding a zero of polynomial graphicaly we only take zero from x axis why not from y axis ?​

Answer 1

Answer:

If we graph this polynomial as y = p(x), then you can see that these are the values of x where y = 0. In other words, they are the x-intercepts of the graph. The zeros of a polynomial can be found by finding where the graph of the polynomial crosses or touches the x-axis.

Answer 2

Let y=f(x) be the polynomial.

So, for the values of x, for which y is 0, are the zeroes of the polynomial f(x). Now, when f(x) is traced in the x-y plane, there will point intersecting both x and y-axis/ either axis/ none of the axis. Here's the lighter, the intersections.

Points of intersection with x-axis:

Where the graph intersects the x-axis, the coordinate would be, y=0, x=x1( x1 being any number). This means at this point the polynomial, f(x) will have the values (x1,0).

That is why, when we put x=x1 in f(x), the value turns out to be 0, i.e. x1 is a zero of the polynomial f(x).

HOPE IT HELPS!!!