y ∝ √ x If y = 45 when x = 81 find, x when

Question

y
∝
√
x
If
y
=
45
when
x
=
81
find,
x
when
y
=
100

in progress 0
Ngọc Diệp 4 years 2021-07-23T17:25:57+00:00 1 Answers 18 views 0

Answers ( )

  1. trungdung22
    0
    2021-07-23T17:27:37+00:00
    Reply

    Answer:

    x = 400 when y = 100

    Step-by-step explanation:

    This is a question in relation to direct variation.

    y ∝ \sqrt{x}

    y = k \sqrt{x}

    Given that, y = 45, x = 81. Then;

    45 = k \sqrt{81}

    45 = 9k

    k = \frac{45}{9}

    k = 5

    Thus the relationship among the variables is;

    y = 5 \sqrt{x}

    If y = 100, then;

    100 = 5 \sqrt{x}

    \sqrt{x} = \frac{100}{5}

    \sqrt{x} = 20

    x = (20)^{2}

    x = 400

    Therefore, x = 400 when y = 100.

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