Q. 183.7( 3 Votes )

Which of the following is not true?
A. (7 + 8) + 9 = 7 + (8 + 9)

B. (7 × 8) × 9 = 7 × (8 × 9)

C. 7 + 8 × 9 = (7 + 8) × (7 + 9)

D. 7 × (8 + 9) = (7 × 8) + (7 × 9)

Answer :

LHS = left hand side


RHS = Right hand side


A. (7 + 8) + 9 = 7 + (8 + 9)


Is true due to associative property of addition.


B. (7 × 8) × 9 = 7 × (8 × 9)


Is true due to associative property of multiplication.


C. LHS = 7 + 8 × 9


= 7 + 72


= 79


RHS = (7+8) × (7+9)


= 15× 16 = 240


As LHS ≠ RHS,


It is incorrect.


D. 7 × (8 + 9) = (7 × 8) + (7 × 9)


It is true due to distributive property of addition over multiplication.

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