Verified answer

1. x varies directly with y, such that when x is 15 y is 5, what is y when x is -3?

• x = ky
• x = 15, y = 5
• 15 = k • 5
• 15/5 = k
• 3 = k

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• x = 3y
• x = -3, y = ?
• -3 = 3y
• -3/3 = y
• -1 = y

• The value of y is -1.

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2. Z varies directly with the square of t, such that Z is 12 when t is 2. What is Z when t is -1?

• z = kt²
• z = 12, t = 2
• 12 = k • 2²
• 12 = k • 4
• 12/4 = k
• 3 = k

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• z = 3t²
• z = ?, t = -1
• z = 3 • -1²
• z = 3 • 1
• z = 3

• The value of z is 3.