Question

find the values that make the expression undefined 3x-2 over y^2+49

Answer 1

What makes this undefined?

Answer 2

Well, its undefined when the denomintor is 0. Lets set the denominator to zero and solve for y

Answer 3

y^2+49=0

Answer 4

subtract 49 from both sides

Answer 5

Then take the square root of both sides. leaving you with: y=?

Answer 6

7?

Answer 7

exactly

Answer 8

but,. on second look, the denomintor never goes to zero, can you see why?

Answer 9

because 7^2 = 49 +49 which then equals a positive number

Answer 10

exactly, and thats why this function is never undefined

Answer 11

can y= -(7^2)?

Answer 12

Well, let me as you this, if i plug -7 into y^2, what do i get?

Answer 13

ask*

Answer 14

you get positive 49 right?

Answer 15

so, because the y is squared, no matter what number you put in there, you will get a positive number

Answer 16

thus, the denominator will never =0

Answer 17

there is no value for which this expression is undefined

Answer 18

but can't the (7^2) be multiplied first and then the negative multiplies it on the outside?

Answer 19

no it is impossible ......there is no value for which this expression in undefined

Answer 20

thats not possible, beacuse that would mean, that the negative sign would also have to affect the whole denominator:
-(7^2+49)=-49-49=still defined