Question

find (-31)*(-100),(-25)*(-72),(-83)*(-28)

Answer 1

Given :

$(-31)*(-100)\\(-25)*(-72)\\(-83)*(-28)$

To find :

$(-31)*(-100)\ =?\\(-25)*(-72)\ =?\\(-83)*(-28)\ =?$

Solution

$(-31)*(-100)\ =3100$

The two $-$ sign gives the result positive

$-25 \ * -72 \\=\ 1800$

The two $-$ sign gives the result positive

$(-83)*(-28)\\=\ 2324$

The two $-$ sign gives the result positive

It means

$- * -= +\\- * +=-\\+ * += +\\+ *-\ =-$