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secondary 4 | A Maths
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wp
Wp

secondary 4 chevron_right A Maths

rate of change

Date Posted: 6 years ago
Views: 367

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Jiayang
Jiayang's answer
1883 answers (Tutor Details)
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wp
Wp
6 years ago
thank u
wp
Wp
6 years ago
but how did u prove the first one ?
wp
Wp
6 years ago
the x=r+7
Jiayang
Jiayang
6 years ago
When r=3, x=10. Both parameters are increasing at the same rate => their difference is a constant. So x is always 7 more than r.
wp
Wp
6 years ago
i also don’t understand how u got r=7
Jiayang
Jiayang
6 years ago
R=7 is the length of r after 20s. Every second it increases by 0.2cm, after 20s it must've increased by 20x0.2=4cm. Therefore, 3+4=7
wp
Wp
6 years ago
i see, thanks for clarifying my doubts