Question

tìm x,y thuộc z, biết:

a) (x-3).(y+5)=7

b) (2x - 1). (2y +1) = 21

các bạn ơi giúp mk với gấp lắm

Answer 1

a:(x-3)(y+5)=7

\(\Leftrightarrow\left(x-3;y+5\right)\in\left\{\left(1;7\right);\left(7;1\right);\left(-1;-7\right);\left(-7;-1\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(4;2\right);\left(10;-4\right);\left(2;-12\right);\left(-4;-6\right)\right\}\)

b: \(\left(2x-1\right)\left(2y+1\right)=21\)

\(\Leftrightarrow\left(2x-1;2y+1\right)\in\left\{\left(1;21\right);\left(21;1\right);\left(-1;-21\right);\left(-21;-1\right);\left(3;7\right);\left(7;3\right);\left(-3;-7\right);\left(-7;-3\right)\right\}\)

hay \(\left(x,y\right)\in\left\{\left(1;10\right);\left(11;0\right);\left(0;-11\right);\left(-10;-1\right);\left(2;3\right);\left(4;1\right);\left(-1;-4\right);\left(-3;-2\right)\right\}\)