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प्रश्न
Which of the following is not true?
विकल्प
(7 + 8) + 9 = 7 + (8 + 9)
(7 × 8) × 9 = 7 × (8 × 9)
7 + 8 × 9 = (7 + 8) × (7 + 9)
7 × (8 + 9) = (7 × 8) + (7 × 9)
MCQ
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उत्तर
7 + 8 × 9 = (7 + 8) × (7 + 9)
Explanation:
a. We have, (7 + 8) + 9 = 7 + (8 + 9)
LHS = (7 + 8) + 9
= 15 + 9
= 24
RHS = 7 + (8 + 9)
= 7 + 17
= 24
LHS = RHS
So, it is true.
b. We have, (7 × 8) × 9 = 7 × (8 × 9)
LHS = (7 × 8) × 9
= 56 × 9
= 504
RHS = 7 × (8 × 9)
= 7 × 72
= 504
LHS = RHS
So, it is true.
c. We have, 7 + 8 × 9 = (7 + 8) × (7 + 9)
LHS = 7 + 8 × 9
= 7 + 72
= 79
RHS = (7 + 8) × (7 + 9)
= 15 × 16
= 240
∴ 79 ≠ 240
∴ LHS ≠ RHS
So, it is false.
d. We have, 7 × (8 + 9) = (7 × 8) + (7 × 9)
LHS = 7 × (8 + 9)
= 7 × 17
= 119
RHS = (7 × 8) + (7 × 9)
= 56 + 63
= 119
∴ LHS = RHS
So, it is true.
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