Answer:
A : 25
Step-by-step explanation:
In a neutral atom, the number of electrons is equal to the number of protons. The atomic number indicates the number of protons.
The mass number is the sum of the number of neutrons and the number of protons.
mass number=protons+neutrons
As we know from the atomic number, the number of neutrons is 14 and the number of electrons is 11.
mass number = 14 + 11
9514 1404 393
Answer:
24 cm²
Step-by-step explanation:
To find the area of the trapezium, we must know the length CD. That means we must know the length BC. Fortunately, the perimeter of ABCF is given, so we have ...
P = 2(AB +BC)
BC = (P/2) -AB = (20 cm)/2 - 6 cm = 4 cm
Then CD is ...
CD = BD -BC = 9 cm -4 cm = 5 cm
The area of the trapezium is given by the formula ...
A = (1/2)(b1 +b2)h
A = (1/2)(5 cm + 3 cm)(6 cm) = 24 cm²
The area of trapezium CDEF is 24 cm².
The answer is 12x+4 and 2(6x+2)
Hope it helps.