trinity enlarged her favorite 3inch by 5inch photo to a size that was 3 times its original size. what is the area, in square inches, of the enlarged photograph?

Question

I'm checking my daughter's homework and I'm trying to figure out if I'm wrong or is she wrong. She multiplied 3*3*3. According to the problem i entered wouldn't it be 3*3=9, 5*3=15. Then 9*15=135inches squared

Answer 1

You are correct.  Area scales as the square of the scaling factor.  

 

But your daughter is already jumping ahead to the volume problem!  If it was a three dimensional object then the volume of the object would scale as the cube of the scaling factor.  

Answer 2

Hi Anthony.  You are right.

 

Since the enlargement is 3 times the original size, we multiply each dimension by its scale factor.  This is called a dilation.  Since the scale factor is 3 because it is enlarged 3x,

 

3 inch × 3 = 9 inch

 

5 inch × 3 = 15 inch

 

 

The new size is  9 inch by 15 inch.

 

Next, multiply these new dimensions to get the area.

 

Area = 9 inch × 15 inch

Area = 135 square inches