SAT II Math I : Solving Functions

Study concepts, example questions & explanations for SAT II Math I

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Example Questions

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Example Question #10 : Quadratic Inequalities

Which value for  would satisfy the inequality ?

Possible Answers:

Not enough information to solve

Correct answer:

Explanation:

First, we can factor the quadratic to give us a better understanding of its graph. Factoring gives us: . Now we know that the quadratic has zeros at  and . Furthermore this information reveals that the quadratic is positive. Using this information, we can sketch a graph like this: 

Sketch inequality

We can see that the parabola is below the x-axis (in other words, less than ) between these two zeros  and .

The only x-value satisfying the inequality  is .

The value of  would work if the inequality were inclusive, but since it is strictly less than instead of less than or equal to , that value will not work.

Example Question #1 : Solving Other Functions

Simplify:

You may assume that  is a nonnegative real number.

Possible Answers:

Correct answer:

Explanation:

The best way to simplify a radical within a radical is to rewrite each root as a fractional exponent, then convert back.

First, rewrite the roots as exponents.

Multiply the exponents, per the power of a power rule:

Example Question #111 : Functions And Graphs

Define functions  and .

 for exactly one value of  on the interval .

Which of the following statements is correct about ?

Possible Answers:

Correct answer:

Explanation:

Define 

Then if ,

it follows that

,

or, equivalently,

.

By the Intermediate Value Theorem (IVT), if  is a continuous function, and  and  are of unlike sign, then  for some . As a polynomial,  is a continuous function, so the IVT applies here.

Evaluate  for each of the following values: :

Only in the case of  does it hold that  assumes a different sign at both endpoints - . By the IVT, , and , for some .

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