What is the perimeter (please explain your answer)

B. 38 mm

Step-by-step explanation:

The Perimeter of a Shape

The perimeter of a given shape is the sum of all exterior lengths surrounding the shape.

The figure shows a shape where all the external measures are given except the leftmost side.

This length is the sum of 3 mm + 10 mm = 13 mm.

Now calculate the perimeter:

P = 4 mm + 3 mm + 10 mm + 8 mm + 13 mm = 38 mm

B. 38 mm

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

answer: your answer is a