In step 4 of the construction of a perpendicular line through a point why must the compass point be placed on the point where the arc intersects with the original line ?

Mr. walker gave his class the function f(x) = (x + 3)(x + 5). four students made a claim about the function. each student’s claim is below. jeremiah: the y-intercept is at (15, 0). lindsay: the x-intercepts are at (–3, 0) and (5, 0). stephen: the vertex is at (–4, –1). alexis: the midpoint between the x-intercepts is at (4, 0). which student’s claim about the function is correct?

The factorization of 8x3 -125 is (2x-5)(jx2 +kx+25)

Me because some of question i don’t understand