If a/b=c/d. Which statement is not true?

A. b/c=d/a is not true.

let's use a real example

a/b = c/d

1/4 = 2/8

A. b/c = d/a

4/2 = 8/1 => 2 is not equal to 8. So this isnot true

B. b/d = a/c

4/8 = 1/2 ==> 1/2 = 1/2, which is correct

C. ad = bc is cross multiplication of the original

1(8) = 4 (2) ==> 8 = 8, which is correct

D. b/a = d/c

4/1 = 8/2 ==> 4 = 4, which is correct

A

Answer c is obtained by cross-multiplication, and the other two can be derived from it by algebraic operations. A, on the other hand cannot. For example, if we start with:

1/4 = 3/6, it will not be true that 4/3 = 6/1.

Uhhh... A. But A can be true, provided a^2=c^2 ie +-a = +-c (not stated in the question) However, all the other cases are true for any value or a b c d.

Cross multiply your terms,

ad=bc

Now cross multiply all of them and compare,

A)ab=cd

B)bc=ad

C)ad=bc

D)bc=ad

One of these is not like the others and its A), it may be true but it can't be verified with the information given.

first, change a/b=c/d into a*d=b*c

we check the optionals one by one to proof the answer

A:

it absolutely wrong, because the mark isn't / but it should be *

B:

it's true. let's see.

a*d=b*c

a/c*d=b

a/c=b/d or b/d=a/c

C:

it's true, of course. ad=bc is as same as a*d=b*c

D:

it's true. let's check.

a*d=b*c

a*d/c=b

d/c=b/a or b/a=d/c

so the answer is A

A)

b/c = d/a

b = c(d/a)

b = (cd)/a

ab = cd (this statement is not true of a/b = c/d)

∴ the answer is A.

A is not true