question_answer 18)

Starting from \[\text{(}-\text{1)}\times \text{5}\], write various products showing some pattern to show\[(-1)\times (-1)=1\].

Answer:

                \[(-1)\times 5=-5\]                                                          \[(-1)\times 4=-4\]          \[[=(-5)+1]\]                                         \[(-1)\times 3=-3\]          \[[=(-4)+1]\] \[(-1)\times 2=-2\]                          \[[=(-3)+1]\] \[(-1)\times 1=-1\]                          \[[=(-2)+1]\] \[(-1)\times 0=0\]                            \[[=(-1)+1]\] \[(-1)\times (-1)=1\]                       \[[=0+1]\].