New SAT Math - Calculator : New SAT Math - Calculator

Study concepts, example questions & explanations for New SAT Math - Calculator

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Example Questions

Example Question #6 : Simplifying Square Roots

What is the simplified (reduced) form of \displaystyle \sqrt{96}?

Possible Answers:

\displaystyle 8\sqrt{3}

\displaystyle 2\sqrt{48}

\displaystyle 4\sqrt{6}

\displaystyle 2\sqrt{24}

It cannot be simplified further.

Correct answer:

\displaystyle 4\sqrt{6}

Explanation:

To simplify a square root, you have to factor the number and look for pairs. Whenever there is a pair of factors (for example two twos), you pull one to the outside.

Thus when you factor 96 you get
\displaystyle \\ \sqrt{96}=\sqrt{2\cdot 2\cdot 2\cdot2\cdot2\cdot 3}\\ \\=2\cdot 2\sqrt{2\cdot 3}\\ \\=4\sqrt{6}

Example Question #10 : Simplifying Square Roots

Which of the following is equal to \displaystyle \small \sqrt{1260}?

Possible Answers:

\displaystyle \small 10\sqrt{7}

\displaystyle \small 6\sqrt{35}

\displaystyle \small 60\sqrt{7}

\displaystyle \small 30\sqrt{3}

\displaystyle \small 26\sqrt{35}

Correct answer:

\displaystyle \small 6\sqrt{35}

Explanation:

When simplifying square roots, begin by prime factoring the number in question. For \displaystyle \small 1260, this is:

\displaystyle \small 1260=2*2*3*3*5*7

Now, for each pair of numbers, you can remove that number from the square root. Thus, you can say:

\displaystyle \small \sqrt{1260}=2*3*\sqrt{35}=6\sqrt{35}

Another way to think of this is to rewrite \displaystyle \small \sqrt{1260} as \displaystyle \small \sqrt{4}*\sqrt{9}*\sqrt{35}. This can be simplified in the same manner.

Example Question #261 : New Sat Math Calculator

Simplify the following square root: 

\displaystyle \sqrt{83}

Possible Answers:

\displaystyle 8\sqrt{3}

\displaystyle 4\sqrt{67}

\displaystyle 2\sqrt{41.5}

The square root is already in simplest form.

\displaystyle 5\sqrt{13}

Correct answer:

The square root is already in simplest form.

Explanation:

We need to factor the number in the square root and find pairs of factors inorder to simplify a square root.

Since 83 is prime, it cannot be factored.

Thus the square root is already simplified.

Example Question #12 : Simplifying Square Roots

Right triangle \displaystyle \Delta ABC has legs of length \displaystyle 5. What is the exact length of the hypotenuse?

Possible Answers:

\displaystyle 2\sqrt{5}

\displaystyle 5\sqrt{5}

\displaystyle 10

\displaystyle 25\sqrt{2}

\displaystyle 5\sqrt{2}

Correct answer:

\displaystyle 5\sqrt{2}

Explanation:

If the triangle is a right triangle, then it follows the Pythagorean Theorem. Therefore:

\displaystyle a^2 + b^2 = c^2 ---> \displaystyle 5^2 + 5^2 = 50 = c^2

\displaystyle c= \sqrt50

At this point, factor out the greatest perfect square from our radical:

\displaystyle \sqrt{50} = \sqrt{25 \cdot 2}

Simplify the perfect square, then repeat the process if necessary.

\displaystyle \sqrt{25 \cdot 2} = 5\sqrt2

Since \displaystyle 2 is a prime number, we are finished!

Example Question #13 : Simplifying Square Roots

Simplify: \displaystyle \sqrt{5000}

Possible Answers:

\displaystyle 50\sqrt{2}

\displaystyle 20\sqrt{5}

\displaystyle 200\sqrt{5}

\displaystyle 2\sqrt{50}

\displaystyle 5\sqrt{20}

Correct answer:

\displaystyle 50\sqrt{2}

Explanation:

There are two ways to solve this problem. If you happen to have it memorized that \displaystyle 2500 is the perfect square of \displaystyle 50, then \displaystyle \sqrt{5000} = \sqrt{2500 \cdot 2} = 50\sqrt 2   gives a fast solution.

If you haven't memorized perfect squares that high, a fairly fast method can still be achieved by following the rule that any integer that ends in \displaystyle 00 is divisible by \displaystyle 25, a perfect square.

\displaystyle \sqrt{5000} = \sqrt{25 \cdot 200} = 5\sqrt{200}

Now, we can use this rule again:

\displaystyle 5\sqrt{200} = 5\sqrt{25 \cdot 8} = 25 \sqrt {8}

Remember that we multiply numbers that are factored out of a radical.

The last step is fairly obvious, as there is only one choice:

\displaystyle 25 \sqrt{8} = 25\sqrt {4 \cdot 2} = 50\sqrt 2

Example Question #14 : Simplifying Square Roots

Simplify: \displaystyle \sqrt{3240}

Possible Answers:

\displaystyle 35\sqrt{3}

\displaystyle 9\sqrt{40}

\displaystyle 15\sqrt{235}

\displaystyle 9\sqrt{57}

\displaystyle 18\sqrt{10}

Correct answer:

\displaystyle 18\sqrt{10}

Explanation:

A good method for simplifying square roots when you're not sure where to begin is to divide by \displaystyle 10\displaystyle 4 or \displaystyle 16, as one of these generally starts you on the right path. In this case, since our number ends in \displaystyle 0, let's divide by \displaystyle 10:

\displaystyle \sqrt{3240} = \sqrt{324 \cdot 10}

As it turns out, \displaystyle 324 is a perfect square!

\displaystyle \sqrt{324 \cdot 10} = 18\sqrt{10}

Example Question #15 : Simplifying Square Roots

Simplify: \displaystyle 8\sqrt{136}

Possible Answers:

\displaystyle 24\sqrt{3}

\displaystyle 16\sqrt{34}

\displaystyle 10\sqrt{34}

\displaystyle 16\sqrt{8}

\displaystyle 8\sqrt{136}

Correct answer:

\displaystyle 16\sqrt{34}

Explanation:

Again here, if no perfect square is easily recognized try dividing by \displaystyle 10\displaystyle 4, or \displaystyle 16.

\displaystyle 8\sqrt{136} = 8\sqrt{4 \cdot 34} = 16 \sqrt{34}

Note that the \displaystyle 2 we obtained by simplifying \displaystyle \sqrt{4} is multipliednot added, to the \displaystyle 8 already outside the radical.

Example Question #262 : New Sat Math Calculator

Simplify:

\displaystyle \sqrt{48}

Possible Answers:

\displaystyle 6

\displaystyle 4\sqrt3

\displaystyle \sqrt{48}

\displaystyle 3\sqrt{4}

Correct answer:

\displaystyle 4\sqrt3

Explanation:

To solve, simply find a perfect square factor and pull it out of the square root.

Recall the factors of 48 include (16, 3). Also recall that 16 is a perfect square since 4*4=16.

Thus,

\displaystyle \sqrt{48}\Rightarrow \sqrt{16*3}\Rightarrow \sqrt{4^2*3}\Rightarrow 4\sqrt{3}

Example Question #812 : New Sat

Solve:

\displaystyle \sqrt{20}+\sqrt{45}=?

Possible Answers:

\displaystyle 4\sqrt{5}

\displaystyle 5\sqrt{20}

\displaystyle 2\sqrt{5}

\displaystyle 5\sqrt{5}

\displaystyle \sqrt{65}

Correct answer:

\displaystyle 5\sqrt{5}

Explanation:

The trick to these problems is to simplify the radical by using the following rule:  \displaystyle \sqrt{ab}=\sqrt{a}*\sqrt{b} and \displaystyle a\sqrt{b}+c\sqrt{b}=(a+c)\sqrt{b} Here, we need to find a common factor for the radical. This turns out to be five because  Remember, we want to include factors that are perfect squares, which are what nine and four are. Therefore, we can rewrite the equation as: \displaystyle \sqrt{20}+\sqrt{45}=2\sqrt{5}+3\sqrt{5}=5\sqrt{5}.

Example Question #263 : New Sat Math Calculator

 

 
 
 

Each of the following is equal to \displaystyle \sqrt[4]{x^3} for all values of \displaystyle x EXCEPT?

 
 
 
Possible Answers:

\displaystyle \sqrt{x^{\frac{2}{3}}}

 
 
 

\displaystyle \sqrt{(\sqrt{x^3})}

 
 
 

\displaystyle x^{\frac{3}{4}}

 
 
 

\displaystyle (\sqrt[4]{x})^3

 
 
 

 

 
 
 

 

 
 
 

Correct answer:

\displaystyle \sqrt{x^{\frac{2}{3}}}

 
 
 
Explanation:

This question may look daunting, especially if you start out by trying pick values or \displaystyle x and solving. This plan of attack will work, but you're likely going to be dealing with some messy numbers. Instead we want to recall some of our exponent and root rules. 

Let's look at this answer choice: 

\displaystyle \sqrt{(\sqrt{x^3})}

This double square root is the same as a fourth root. Think about it, you have a square times a square- which is the same thing as \displaystyle 2\times2. Thus,  \displaystyle \sqrt{(\sqrt{x^3})}=\sqrt[4]{x^3} so this choice can be eliminated. 

Next, let's look at this answer choice: 

\displaystyle x^{\frac{3}{4}}

For this choice, we need to recall our exponent rules. Remember, whenever we have a value raised to a fractional power, the denominator of that fraction is equal to the root number. In this case, \displaystyle 4. Thus, \displaystyle x^{\frac{3}{4}}=\sqrt[4]{x^3}

Now, let's look at this answer choice:

\displaystyle (\sqrt[4]{x})^3

A key rule to remember here is that order doesn't not matter when dealing with roots and powers. Thus, taking the  root of a number and then cubing it will result in the same value as cubing a number and then taking the  root . 

This leaves us with: 

\displaystyle \sqrt{x^{\frac{2}{3}}}

If we tried to break this down a bit, we could take the third root of \displaystyle x^2, which would leave us with: 

\displaystyle \sqrt{\sqrt[3]{x^2}}. This will not equal \displaystyle \sqrt[4]{x^3}

 

 
 
 
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