Algebra
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SAT Math › Algebra
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
.
According to Heron's Formula, the area of a triangle with side lengths of a, b, and c is given by the following:
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.
Simplify:
Explanation
Rewrite in their imaginary terms.
Expand the expression .
Explanation
Use the FOIL method (first, outer, inner, last) to multiply expressions and combine like terms:
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.
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.
Three consecutive even numbers add to 42. What is the middle number?
Explanation
Let = 1st even number,
= 2nd even number, and
= 3rd even number.
Then the equation to solve becomes .
Thus , so the middle number is 14.
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.
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 .
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; y – y = 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