Question

How do you simplify `(5+i)(8+i)` and write the complex number in standard form?

Answer 1

`39+13i`

Explanation:

`color(blue)((5+i))color(brown)((8+i))`

Multiply everything in the RHS brackets by everything in the LHS brackets.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
color(blue)(
color(brown)(
`[color(blue)(5xx)color(brown)(8)]+[color(blue)(5xx)color(brown)(i)]" "+" "[color(blue)(ixx)color(brown)(8)]+[color(blue)(ixx)color(brown)(i)]`

`40+5i+8i+(-1)`

`39+13i`