smc-4444-10-Identify graphs

Exponential, SMB-006 MC

Which graph best represents the equation `y = 5^(−x)`?

A.		B.
C.		D.

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`D`

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`y=5^(−x)= 1/(5^x)`

`text(At)\ \ x = 0, \ y = 1`

`text(As)\ \ x -> ∞, \ y -> 0`

`=> D`

Which of the following best represents the graph of `y = 10 (0.8)^x`?

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`A`

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`\text{By elimination:}`

♦ Mean mark 41%.

`\text{When} \ x = 0 \ , \ y = 10(0.8) ^0 = 10`

`-> \ text{Eliminate B and D}`

`text(As)\ \ x→oo, \ y→0`

`-> \ text{Eliminate C}`

`=> A`

Which graph best represents `y = 3^x`?

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`D`

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`y = 3^x\ \ text(passes through)\ \ (0,1)\ \text(and is exponential.)`

`=> D`

The diagram shows the graph of an equation.

Which of the following equations does the graph best represent?

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`C`

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`text(Graph is a parabola that passes through)\ (0, 1).`

`=> C`

Which of the following graphs best represents the equation `y = a^x`, where `a` is a positive number greater than 1?

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`D`

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♦ Mean mark 48%

`text(At) \ x=0,\ y=1`

`text(As)\ x uarr, \ \ y ↑\ text(exponentially)`

`=>D`