Question

which of the following is a true statement a) if AB=CD,then 3CD=3(CD+1). b)if AB=CD,then AB-CD=A-C+B-D. c)if AB=CD,thenAB+EF=CD+EF d)if AB=CD, then 2AB=2A+2B

Answer 1

C. If AB = CD, then AB + EF = CD + EF.

Answer 2

a) if AB = CD, then 3CD = 3(CD + 1) NOT TRUE

example: AB = CD = 1, then 3CD = (3)(1)=3 and 3(CD + 1) = 3(1 + 1) = 3(2) = 6

b) if AB = CD, then AB - CD = A - C + B - D NOT TRUE (it does not make sense because A, B, C and D are points)

c) if AB = CD, then AB + EF = CD + EF TRUE

because

AB = CD |add EF to both sides

AB + EF = CD + EF

d) if AB = CD, then 2AB = 2A + 2B NOT TRUE (it does not make sense because A and B are points).