SAT II Math I : Solving Equations

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

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Example Questions

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Example Question #92 : Single Variable Algebra

Give the set of all real solutions of the following equation: 

Possible Answers:

No solution

Correct answer:

Explanation:

 can be seen to fit the perfect square trinomial pattern:

The equation can therefore be rewritten as 

Multiply both sides of the equation by the least common denominator of the expressions, which is :

Distributing and collecting like terms, we get

Multiplying both sides by :

This can be solved using the  method. We are looking for two integers whose sum is  and whose product is . Through some trial and error, the integers are found to be 2 and 12, so the above equation can be rewritten, and solved using grouping, as

By the Zero Product Principle, one of these factors is equal to zero:

Either: 

Or:

 

Both solutions can be confirmed by substitution; the solution set is 

Example Question #91 : Solving Equations

A polynomial of degree four has as its lead term  and has rational coefficients. Two of its zeroes are  and . What is this polynomial?

Possible Answers:

Cannot be determined

Correct answer:

Explanation:

A fourth-degree, or quartic, polynomial has four zeroes, if a zero of multiplicity  is counted  times. Since its lead term is , we know that

A polynomial with rational coefficients has its imaginary zeroes in conjugate pairs. Since  is such a polynomial, then, since  is a zero, so is its complex conjugate ; similarly, since  is a zero, so is its complex conjugate . Substituting these four values for the four  values: 

This can rewritten as

or

Multiply the first two factors using the difference of squares pattern, then the square of a binomial pattern:

Multiply the last two factors similarly:

Thus,

Multiply:

                            

                            

                       

       

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Example Question #101 : Single Variable Algebra

Give the set of all real solutions of the equation   .

Possible Answers:

None of these

Correct answer:

None of these

Explanation:

Set . Then 

 can be rewritten as

Substituting  for  and  for , the equation becomes 

,

a quadratic equation in .

This can be solved using the  method. We are looking for two integers whose sum is  and whose product is . Through some trial and error, the integers are found to be  and 4, so the above equation can be rewritten, and solved using grouping, as

By the Zero Product Principle, one of these factors is equal to zero:

Either:

Substituting back:

, or 

However, this does not hold for any real value of . No solution is yielded here.

Or:

Substituting back:

, or 

,

the only solution. This is not among the choices.

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