I will mark brainiest(pls help me :c)

86.48 I guess

Step-by-step explanation:

13.74m

Step-by-step explanation:

Perimeter of shaded region:

Perimeter of shaded region=area of rectangle- area of semicircle

l×w‐(πr²) - -> diameter of circle‐6m; Radius‐3

=8×6‐(3.14×3×3)

=42— 28.26=13.74m

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