The answer must be

since the triangular pyramid has 4 faces and each has an area of 30

we should multiply that by 4 , so :
Answer:
two: +1 and -1
Step-by-step explanation:
If a number is equal to its own reciprocal, it will satisfy the equation ...
x = 1/x
Multiplying by x and subtracting 1 gives ...
x^2 -1 = 0
This factors as ...
(x -1)(x +1) = 0
By the zero product rule, the solutions are those values of x that make one or more factors zero:
x = 1
x = -1
There are two self-reciprocals.
Area of a semi-circle = 1/2 x x r square.
area of larger semi circle
= 1/2 x x 10 square
= 50
area of smaller semi circle
= 1/2 x x 5 square
= 12.5
Total area = 50 + 12.5 = 196 cm square ( to 3 sf ) or 62.5
F(x) +g(x)
= (5x -2) +(2x +1)
= 7x -1 . . . . . . . . . . . . matching selection A