Find the values of the following expressions. For each pair, first try to guess whether they have the same value. Class 7
mediumFind the values of the following expressions. For each pair, first try to guess whether they have the same value. Class 7
Question 1.
Find the values of the following expressions. For each pair, first try to guess whether they have the same value. When are the two expressions equal? Class 7
(a) (6 + 10) – 2 and 6 + (10 – 2)
Solution:
(6 + 10) - 2 = 16 - 2 = 14
and 6 + (10-2) = 6 + 8 = 14
Equal
(b) 16 - (8 - 3) and (16 - 8) - 3
Solution:
16 - (8 - 3) = 16 - 5 = 11
and (16 - 8) - 3 = 8 - 3 = 5
Not equal
(c) 27 - (18 + 4) and 27 + (-18 - 4)
Solution:
27 - (18 + 4) = 27 - 22 = 5
and 27 + (-18 - 4) = 27 + (-22) = 5
Equal
Question 2.
In each of the sets of expressions below, identify those that have the same value. Do not evaluate them, but rather use your understanding of terms. Class 7
(a) 319 + 537, 319 - 537, - 537 + 319, 537 - 319
Solution:
319 - 537, - 537 + 319 are equal.
(b) 87 + 46 - 109, 87 + 46 - 109, 87 + 46 - 109, 87 - 46 + 109, 87 - (46 + 109), (87 - 46) + 109
Solution:
87 + 46 - 109, 87 + 46 - 109 and 87 + 46 - 109 are trivially equal because these are the same expressions.
87 - (46 + 109) and (87 - 46) + 109 are not equal. But 87 - 46 + 109 and (87 - 46) + 109 are equal.