According to the number line, which statement MUST be true?

Atriangle with all sides of equal length is a/an triangle. a. right b. scalene c. equilateral d. isosceles

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)