Which statement is not true? a. the sum of a rational number and an irrational number is irrational. b. the sum of two rational numbers is rational. c. the product of two irrational numbers is irrational. d. the sum of two rational numbers is rational.

Option (C) is the incorrect one.

Because product of two irrational numbers is not "Always" irrational.

as in the case below,

√5 × √5 = 5

We arealdy know that √5 is an irrational number, and after multiplying that with another irrational number √5, we got a rational number that is 5.

The given graph is a vertical hyperbola with centre,(h,k) =(1,-2),

And vertices are (1,2),(1,-6) .

So in the given graph, we have h =1, k =-2, k-a=-6, k+a=2

That gives a = 4

So for the vertices, answer is (1,2),(1,-6) .