Y varies directly with √x+5. y = 4 when x = -1. Find y when x = 11?

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  • alex
    Lv 7
    4 months ago

    hint:

    y varies directly with √(x + 5)---> y = k√(x + 5)then usey = 4 when x = -1to find the constant k...

  • 4 months ago

    y varies directly with √x + 5. 

    y = 4 when x = -1

    y = k(x + 5)^(1/2)

    4 = k(-1 + 5)^(1/2) 

    4 = k(4)^(1/2)

    4 = 2k

    k = 2

    y = 2(x + 5)^(1/2)  

    y = 8 when x = 11

  • 4 months ago

    y = k(x + 5)^(1/2)

    4 = k(-1 + 5)^(1/2)

    4 = k(4)^(1/2)

    4 = 2k

    k = 2

    y = 2(x + 5)^(1/2)

    y = 2(11 + 5)^(1/2)

    y = 2(16)^(1/2)

    y = 2(4) = 8

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