Question

A classmate said that the vertex of y -5(x +2)-6 is (2, 6). What mistake did your classmate make? What is the correct vertex?

Answer 1

Answer:

The correct vertex said by classmate is (-2, -6).

Solution:

Given, equation of parabola is $y=-5(x+2)^{2}-6$

We have to find mistake did by the classmate and rectify it.

Now we know that, general form of an parabolic equation is

$y=a(x-h)^{2}+k$

where a is an constant and (h, k) is vertex point of the parabola.

So, now by comparison of given parabola equation with general form, h = -2 and k = -6

Then, vertex point will be (-2, -6).

We can say that, classmate mistook the general form as $y=a(x+h)^{2}-k$

So he got h = 2 and k = 6.

Hence, the correct vertex is (-2, -6).