body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} You must have JavaScript enabled to use this site.

Expand menu

Minimize

Start chapters

Home

History

History

{{ item.displayTitle }}

No history yet!

Progress & Statistics

Progress

Student

Teacher

{{ courseTrack.displayTitle }}

{{ statistics.percent }}%

Sign in to view progress

{{ printedBook.courseTrack.name }} {{ printedBook.name }}

$(\N a)b=\N ab$

Theory

$(- a) b = - a b$

The product of a negative and a positive number is negative. $(- 5) \cdot 3 = - 5 \cdot 3 = - 15$