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Secondary 1 | Maths
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David Bryann Caseles
David Bryann Caseles

Secondary 1 chevron_right Maths

please help me for Q7b , thank you

Date Posted: 7 years ago
Views: 992
MISTER MILI
MISTER MILI
7 years ago
Answer is 420.

HCF of the two numbers is 12. 12=2x2x3.

Hence, both numbers must contain the factors 2x2x3. And you can see from part (aii), 144 does indeed contain 2x2x3.

LCM of the two numbers is 5040. From (aiii), 5040=2x2x2x2x3x3x5x7. 5 and 7 are not prime factors of 144. Hence, it has to be prime factor of the 2nd number.

Thus, 2nd number is 2x2x3x5x7=420.

On the contrary, the second number cannot be 5040. If the second number is 5040, the HCF will be 144 instead of 12.

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Bryant Lam Hong Sheng
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