Question

If x^2=36 and y^2=81 which of the following cannot be the value of x+y

A. -15
B. -3
C. 0
D. 3
E. 15

Answer 1

Answer: 0

Explanation:

We can unsquare the squareroots:

x^2=36

Becomes

x=6 (because 6*6 is 36)

similarly,

y^2=81

Becomes:

y=9(because 9*9=81)

When you have a squareroot no matter if it’s negative or positive the result is a positive number.

Now we can solve and eliminate possible solutions.
For A) -9+(-6)=(-15)

For B) (-9)+6=(-3)

For D)(-6)+9=3

For E) 9+6=15

The only one that cannot be made is C)0