SAT Math Question (Thanks!)

y is greater than or equal to (x-2)^2 + 4
y is less than or equal to -(x-2)^2 + 6
The ordered pair (a,5), where a is a constant, satisfies the system of inequalities above. What is the least possible value of a?

Respuesta :

Answer:

1

Step-by-step explanation:

Sometimes the easiest way to answer a question like this one is to graph it.

The point has to be closest to 1,5. It can also be 1,5

So the answer is a=1

Answer:

1

Step-by-step explanation:

Let's plug the point into both inequalities.

[tex]5 \ge (a-2)^2+4[/tex]

[tex]5 \le -(a-2)^2+6[/tex]

We will solve both and see what values of [tex]a[/tex] they both have in common and then determine the least of that set.

Let's start with the first:

[tex]5 \ge (a-2)^2+4[/tex]

Subtract 4 on both sides:

[tex]1 \ge (a-2)^2[/tex]

We are looking for numbers whose squares are less than 1. Those numbers are between -1 and 1.

So this gives me:

[tex]-1\le a-2 \le 1[/tex]

Add 2 on all sides:

[tex]1 \le a \le 3[/tex]

Now let's solve the other inequality:

[tex]5 \le -(a-2)^2+6[/tex]

Subtract 6 on both sides:

[tex]-1 \le -(a-2)^2[/tex]

Multiply both sides by -1:

[tex] 1 \ge (a-2)^2[/tex]

We are already solved this inequality above.

So the solution for [tex]a[/tex] is [tex]1 \le a \le 3[/tex].

The smallest number of that set is 1.