Question

2.(x-5)-3.(x-4)=-6+15.(-3)

3x+4y-xy=16

Answer 1

\(2\left(x-5\right)-3\left(x-4\right)=-6+15\left(-3\right)\)

\(\Leftrightarrow2x-10-3x+12=-51\)

\(\Leftrightarrow2x-3x=-51-12+10\)

\(\Leftrightarrow-x=-53\)

\(\Rightarrow x=53\)

\(3x+4y-xy=16\)

\(\Rightarrow3x-xy+4y=16\)

\(\Rightarrow x\left(3-y\right)-12+4y=16-12\)

\(\Rightarrow x\left(3-y\right)-4\left(3-y\right)=4\)

\(\Rightarrow\left(x-4\right)\left(3-y\right)=4\)

\(\Rightarrow\left(x-4\right);\left(3-y\right)\inƯ\left(4\right)=\left\{\pm1;\pm2;\pm4\right\}\)

Xét bảng

x-4	1	-1	2	-2	4	-4
3-y	4	-4	2	-2	1	-1
x	5	3	6	2	8	0
y	-1	7	1	5	2	4

Vậy...............................