If y - x and x-7 when y-21- find the constant of variation k-

Given, x=7, y=21 y∝ x ⇒ y=kx #160;(where k is a constant of variation) ⇒ k= y x #160; #160; #160; #160;....(1)Substit ...

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Standard XII

Mathematics

Rate of Change

If y ∝ x an...

Question

If $y \propto x$ and $x = 7$ when $y = 21$ , find the constant of variation $(k)$ .

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Solution

Given, $x = 7, y = 21$
$y \propto x$
$\Rightarrow y = k x$ (where $k$ is a constant of variation)
$\Rightarrow k = \frac{y}{x}$ ....(1)
Substituting $x = 7$ and $y = 21$ in equation (1), we get
$k = \frac{21}{7} = 3$
$∴$ constant of variation $(k) = 3$ .

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If y∝x and x=7 when y=21, find the constant of variation (k).

Given, x=7,y=21y∝x⇒y=kx (where k is a constant of variation)⇒k=yx ....(1)Substituting x=7 and y=21 in equation (1), we getk=217=3∴ constant of variation (k)=3.

If $y \propto x$ and $x = 7$ when $y = 21$ , find the constant of variation $(k)$ .

Given, $x = 7, y = 21$
$y \propto x$
$\Rightarrow y = k x$ (where $k$ is a constant of variation)
$\Rightarrow k = \frac{y}{x}$ ....(1)
Substituting $x = 7$ and $y = 21$ in equation (1), we get
$k = \frac{21}{7} = 3$
$∴$ constant of variation $(k) = 3$ .