Removing Brackets — I
In each of the sets of expressions below, identify those that have the same value. Do not evaluate them; use your understanding of terms. (a) 319 + 537, 319 − 537, −537 + 319, 537 − 319 (b) 87 + 46 − 109, 87 + 46 − 109, 87 + 46 − 109, 87 − 46 + 109, 87 − (46 + 109), (87 − 46) + 109
(a) Write each as a sum of terms and compare:
319 + 537: terms are +319 and +537.
319 − 537: terms are +319 and −537.
−537 + 319: terms are −537 and +319 — same as 319 − 537.
537 − 319: terms are +537 and −319 — different from all above.
Same value: 319 − 537 = −537 + 319.
(b) Identify the terms of each:
87 + 46 − 109: terms +87, +46, −109. (Appears three times — all equal.)
87 − 46 + 109: terms +87, −46, +109. Different.
87 − (46 + 109) = 87 − 46 − 109: terms +87, −46, −109. Different from above.
(87 − 46) + 109 = 87 − 46 + 109: terms +87, −46, +109. Same as 87 − 46 + 109.
Same value: the three expressions '87 + 46 − 109' (×3) have equal values.
Also: '87 − 46 + 109' and '(87 − 46) + 109' have equal values.
Answer: (a) 319 − 537 and −537 + 319 are equal. (b) The first three (87 + 46 − 109) are equal to each other; 87 − 46 + 109 and (87 − 46) + 109 are equal to each other.
