If y is directly proportional to x and y = 5 when x = 2, find the value of y when
x=7.

y = 17.5

Step-by-step explanation:

Given y is directly proportional to x then the equation relating them is

y = kx ← k is the constant of proportion

To find k use the condition y = 5 when x = 2, thus

5 = 2k ( divide both sides by 2 )

2.5 = k

y = 2.5x ← equation of proportion

When x = 7, then

y = 2.5 × 7 = 17.5

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step-by-step explanation:

just for that im not answering

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204