Which of the following are mathematical sentences? Check all that apply.

A. 4x

B. r + 7 = 4

C. x = 1

D. 34

E. 5g = 9

F. 8r = 12

Mathematical sentences is also known as expression.

A:4x can be written as 4 times x.

So, 4x is a mathematical sentence.

B. r+7=4 is an equation so it's not an expression.

Similarly x=1, 5g=9 and 8r=12 all are equations.

So, the correct answer is A: 4x and D. 34.