GMAT® Official Guide 2019 Quantitative Review
(a,b) is not in the shaded region; NOT
sufficient.
(2) This indicates that b > a^2 - 4a, and thus,
(a,b) is in the shaded region; SUFFICIENT.
The correct answer is B;
statement 2 alone is sufficient.
DS01685- If a and b are positive integers, is ¥ab an integer?
(1) Fa is an integer.
(2) b = -faArithmetic
(1) Given that ✓a is an integer, then
a= 4 is possible. If, in addition b = 1, then
ef;;b = ~ is not an integer. However, if,
in addition b = 2, then ~ = ~ = 2 is an
integer; NOT sufficient.
(2) Given that b = ✓a, thenef;;b=~a✓a=~✓c? =✓Y =✓a=bis
an integer; SUFFICIENT.
The corre:ct answer is B;
statement 2 alone is sufficient.