Multiple Choice Question (MCQ)
If a>b and c>d , which of the following must be true?

×
ac>bd

×
a+b>c+d

✓
a+c>b+d

×
ab>cd

×
ad>bc
If a>b and c>d , which of the following must be true?
ac>bd
a+b>c+d
a+c>b+d
ab>cd
ad>bc
ac>bd
If a>b and c>d , the product of sides must not follow the order of size in original inequalities. Multiplying or dividing both sides by a negative number reverses the inequality.
For example,
4 > 3, 1 >2, but 4\times(1) > 3(2), ture
7 > 3, 1 >2, but 7\times(1) < 3(2) , false
a+b>c+d
This statement is obviously false.
a+c>b+d
Addition of two inequalities of the same order will not change the order of the inequalities.
If a>b and c>d
Add the two inequalities, we get
a+c>b+d
ab>cd
This statement is similar to B, which is Not true.
ad>bc
This statement is similar to A, which is also not true.