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CTET Paper II (Mathematics and Science) 21 Dec 2021 Solved Paper

Question : 33 of 150

Marks: +1, -0

-45 × 109 is not the same as

Solution:

Concept:

Distributive property of multiplication over addition:

a \times (b + c) = a \times b + a \times c

must be applied correctly.

Explanation:

Compute

-45 \times 109 = -4905

Option A:

(-45) \times 9 + (-45) \times 100 = (-45) \times (9+100) = -45 \times 109 = -4905

. Same.

Option B:

(-45) \times (100+9) = -45 \times 109 = -4905

. Same.

Option C:

-45 \times 100 + 9 = -4500 + 9 = -4491

. This is not equal to

-4905

Option D:

(-40 - 5) \times 109 = -45 \times 109 = -4905

. Same.

Thus, only option C gives a different result.

Answer:

-45 × 100 + 9

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