Algebra

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SAT Math › Algebra

Questions 1 - 10
1

Given , what is the value of ?

7

11

3

9

5

Explanation

Express as a power of ; that is: .

Then .

Using the properties of exponents, .

Therefore, , so .

2

According to Heron's Formula, the area of a triangle with side lengths of a, b, and c is given by the following:

Hero

where s is one-half of the triangle's perimeter.

What is the area of a triangle with side lengths of 6, 10, and 12 units?

12√5

4√14

8√14

14√2

48√77

Explanation

We can use Heron's formula to find the area of the triangle. We can let a = 6, b = 10, and c = 12.

In order to find s, we need to find one half of the perimeter. The perimeter is the sum of the lengths of the sides of the triangle.

Perimeter = a + b + c = 6 + 10 + 12 = 28

In order to find s, we must multiply the perimeter by one-half, which would give us (1/2)(28), or 14.

Now that we have a, b, c, and s, we can calculate the area using Heron's formula.

Hero

Hero2

3

Simplify:

Explanation

Rewrite in their imaginary terms.

4

Expand the expression .

Explanation

Use the FOIL method (first, outer, inner, last) to multiply expressions and combine like terms:

5

Give the lines y = 0.5x+3 and y=3x-2. What is the y value of the point of intersection?

2

3

4

6

7

Explanation

In order to solve for the x value you set both equations equal to each other (0.5x+3=3x-2). This gives you the x value for the point of intersection at x=2. Plugging x=2 into either equation gives you y=4.

6

Solve for :

Explanation

We want to isolate the variable on one side and numbers on another side. Treat like a normal equation.

Subtract on both sides.

Divide on both sides.

7

Three consecutive even numbers add to 42. What is the middle number?

14

10

12

16

18

Explanation

Let x = 1st even number, x+2 = 2nd even number, and x+4 = 3rd even number.

Then the equation to solve becomes x+(x+2)+(x+4)=42.

3x+6=42

Thus x=12,x+2=14,\ and\ x+4=16, so the middle number is 14.

8

Give the lines y = 0.5x+3 and y=3x-2. What is the y value of the point of intersection?

2

3

4

6

7

Explanation

In order to solve for the x value you set both equations equal to each other (0.5x+3=3x-2). This gives you the x value for the point of intersection at x=2. Plugging x=2 into either equation gives you y=4.

9

Explanation

When multplying exponents, we need to make sure we have the same base.

Since we do, all we have to do is add the exponents.

The answer is .

10

If 7_x_ + y = 25 and 6_x_ + y = 23, what is the value of x?

2

6

7

11

20

Explanation

You can subtract the second equation from the first equation to eliminate y:

7_x_ + y = 25 – 6_x_ + y = 23: 7_x_ – 6_x_ = x; yy = 0; 25 – 23 = 2

x = 2

You could also solve one equation for y and substitute that value in for y in the other equation:

6_x_ + y = 23 → y = 23 – 6_x_.

7_x_ + y = 25 → 7_x_ + (23 – 6_x_) = 25 → x + 23 = 25 → x = 2

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