Why so serious?

Algebra Level 3

$A = \{ x^2 : -2 \leq x \leq 10 \}$

Find the set $A$ .

\left[0,100 \right]

None of the above

\left(4,100 \right)

\left[4,100 \right]

3 solutions

Pranjal Jain
Dec 7, 2014

Plotting graph of $y=x^{2}$ will show that its global minima is at(0,0) and maxima at (10,100)

Moderator note:

Do we really need to graph to solve this problem?

Can you explain what the question really means??? @Pranjal Jain ???

Seeku hhh - 5 years, 11 months ago

The problem asks for the roster form of set A while it gives the set in set-builder form.

Pranjal Jain - 5 years, 11 months ago

Did the question ask us to find the maximum value of $x$ @Pranjal Jain ???

Seeku hhh - 5 years, 11 months ago

I felt so stupid when i got that wrong lol

Benry Burfer - 5 years ago

Akshay Nagaram
Jun 28, 2015

If x =0 then x^2 =0,
x=1 then x^2=1,
x=2 then x^2=4 and so on till x=10 then x^2=100 ,
You can ignore -1 and -2 here because squaring it is the same as of 1 and 2 respectively !!
So the least number you get is 0 and maximum is Hundred !!
Since these are Inclusive the answer is [0,100]

Moderator note:

Careful there, we did not say that $x$ must be an integer.

If you had said that x must be an integer, the set would be {0,1,4,9,16,25,36,49,64,81,100}, rather than the interval from 0 to 100, inclusive.

Cara Sutherland - 4 years, 7 months ago

Jingyang Tan
Jun 30, 2015

i guess and 1/2/3/4/5/6/7/8/7/6/5/34/3/2/1

Moderator note:

We didn't restrict $x$ to be an integer.

What is set?

Praful Jain - 5 years, 9 months ago

A set is a collection of numbers that fit a certain criteria; in this instance, the set had to constitute of any number whose square root is between and including -2 and 10.

Sam Maltia - 5 years, 7 months ago

Why so serious?

3 solutions

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