SAT Math For Dummies with Online Practice. Mark Zegarelli

Чтение книги онлайн.

Читать онлайн книгу SAT Math For Dummies with Online Practice - Mark Zegarelli страница 18

SAT Math For Dummies with Online Practice - Mark  Zegarelli

Скачать книгу

rel="nofollow" href="#fb3_img_img_5b9231e1-2868-517a-bd47-300268f9a1cd.png" alt="math"/> math

      Similarly, you can divide one radical by another by dividing their contents:

math math math

      Example math

      If x is equivalent to the expression shown here, what is the value of math?

      To find the value of x, first simplify math. Begin by multiplying the two radicals in the numerator:

math

      Now, divide the numerator by the denominator and simplify:

math

      Thus, math, so plug this value into math and evaluate:

math

      Simplifying radicals

      In some cases, you can simplify a radical by factoring it and then evaluating one of the factors as a whole number. This is always the case when the value inside the radical is divisible by a square number, such as 4, 9, 16, 25, and so forth.

      For example, here are three radicals that can be simplified by factoring out math and then simplifying this value to 2:

math math math

      Similarly, you can simplify the following three radicals by factoring out math and then simplifying this value to 3:

math math math

      These three radicals can be simplified by factoring out math:

math math math

      And these three can be simplified by factoring out math:

math math math

      An SAT question may ask you to simplify a radical. For example:

      Example Which of the following is the most simplified form of math?

      (A) math

      (B) math

      (C) math

      (D) math

      The number 72 is divisible by 9, so you can factor and simplify math as follows:

math

      Although math is equivalent to math, the question asks you to find the most simplified form of the radical. To do this, notice that 8 is divisible by 4, so you can further factor and simplify math as follows:

math

      This result is the most simplified form of math, so Answer C is correct. (You can also find this answer directly as math.)

      Tip Other opportunities for simplifying radicals may arise when working with the quadratic formula, which includes

Скачать книгу