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Online Quiz (Worksheet A B C D)

Questions Per Quiz = 2 4 6 8 10

Grade 8 - Mathematics
7.42 Problems - VI

Example:
If a+b+c = 6 and a2+b2+c2 = 26, find the value of ab+bc+ca.
Solution:
Given that
a+b+c = 6
Squaring on both sides, we get
(a+b+c)2 = 62
a2+b2+c2+2(ab+bc+ca) = 36
26+2(ab++bc+ca) = 36
2(ab+bc+ca) = 36-26
2(ab+bc+ca) = 10
ab+bc+ca = 10/2
ab+bc+ca = 5


Directions: Solve the following problems. Also write at least ten examples of your own.
Q 1: If a+b+c = 9 and a2+b2+c2 = 45, find the value of ab+bc+ca.
14
16
18
22

Q 2: If a+b+c = 10 and a2+b2+c2 = 56, find the value of ab+bc+ca.
28
22
26
24

Q 3: If a+b+c = 11 and a2+b2+c2 = 71, find the value of ab+bc+ca.
23
29
25
27

Q 4: If a+b+c = 8 and a2+b2+c2 = 40, find the value of ab+bc+ca.
18
16
14
12

Q 5: If a+b+c = 5 and a2+b2+c2 = 21, find the value of ab+bc+ca.
4
8
2
6

Q 6: If a+b+c = 12 and a2+b2+c2 = 88, find the value of ab+bc+ca.
24
30
26
28

Question 7: This question is available to subscribers only!

Question 8: This question is available to subscribers only!


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