*multiplying integers*

*when the integers have different value, ( - or + ) the product is negative.*

*when the integers have same value, ( -,+ )the product is positive.*

*when multiplying integers, count the negative signs*

*odd number = negative*

*even number = positive*

*8.2 textbook*

**10. Estimate and then calculate**

**1) (+17) * (-24) = 408**

**est: (+20) * (-24) = -480**

**I changed 17 to 20 because 17 is close to 20, also i can calculate 20 * 24 in my head fast.**

**Then i used the sign rule to solve this question, when the integers have different value, the product is negative.**

**2) (+37) * (+22) = 814**

**est: (+40) * (+22) =880**

*I changed 37 to 40 because 37 is close to 40, also i can calculate 40 * 22 in my head fast.*

**Then i used the sign rule to solve this question, when the integers have same value, the product is positive.**

**3) (-72) * (+15) = -1080**

**est: (-70) * (+15) = 1050**

**I changed 72 to 70 because 72 is close to 70, also i can calculate 70 * 15 in my head fast.**

**Then i used the sign rule to solve this question, when the integers have different value, the product is negative.**

**4) (-28) * (-47) = 1316**

**est: (-30) * (-45) = 1350**

*I changed 28**to 30, 47 to 45 because 28 is close to 30,and 47 is close to 45 also i can calculate 30 * 45 in my head fast. T**hen i used the sign rule to solve this question, when the integers have same value, the product is positive.*

**12. A telephone company offer its customer a $15 discount per month if they also sign up for internet service. how much is the annual discount?**

**(+12) * (-15) = -180**

**12 groups of (-15)**

**12 month of $15.00 off**

**I used negative sign for $15 because discount means off (getting 15 dollars off each month)**

**annual means one year, there are 12 months in a year, and we have $15.00 off each year.**

**so we need to calculate how much is the annual discount, we multiply 12 by -15 because we have 12 groups of -15.***T**hen we use the sign rule to solve this question, when the integers have different value, the product is negative. 12 * 15 equals 180, the answer has to be negative so, it is -180.*

*13. A hot air balloon is descending at 60 m/min. how far does it descend in 25 min?*

*(+25) * (-60) = -1500*

*25 groups of (-60)*

*25 min of 60 m/ min*

*I used negative sign for 60 m because descend means going down, the hot air balloon is going down 60 m/ min.*

*The hot air balloon is descending at 60 m/min, and the question ask how far does it descend in 25 min? that means, we have 25 groups of 60 because , 60 m/ min, and there are 25 of them. To solve this question we need to multiply 25 by (-60). we can use the sign rule to solve this question, when the integers have different value, the product is negative. 25 * 60 = 1500, the answer has to be negative so it is*

*here is a video that can help you with multiplying integers (with the chip model)*

*multiplying integers is not hard, you can do it!*

*hope my scribe can help you!*

I really like how it was very thought out and I didn't have a hard time understanding this lesson. Great job and thanks for the video! Great job dude!(:

ReplyDeletethanks for your comment;)

DeleteThank you for using multiple questions from the textbook to have some variation in word problems and scenarios. Not only that, but you explained very well, and included a video. Thanks!! :)

ReplyDeleteyour welcome! Hope this can help you;)

Delete