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Online Quiz (Worksheet A B C D)

Questions Per Quiz = 2 4 6 8 10

Grade 8 - Mathematics
7.19 Solving Problems Using Formula for a2-b2

Example: Find the value of 49*51 using formula.

Solution: We can write 49*51 = (50-1)(50+1)
This is the form of (a-b)(a+b) = a2-b2
= 502-12
= 2500-1
= 2499


Directions: Solve the following problems using formula.
Q 1: Find the value of 32*28 using formula.
796
896
996

Q 2: Find the value of 501*499 using formula.
24999
249999
269999

Q 3: Find the value of 69*71 using formula.
4899
4989
4998

Q 4: Find the value of 102*98 using formula.
9996
9986
9976

Q 5: Find the value of 109*111 using formula.
12099
12909
1299

Q 6: Find the value of 62*58 using formula.
3596
3956
4596

Question 7: This question is available to subscribers only!

Question 8: This question is available to subscribers only!


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