ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Math I Videos 77 videos
This video covers how to use cross products to solve for a missing number in a proportion by setting that proportion with a variable over the produ...
GED Math 2.4 Rational Numbers. Lucius's favorite restaurant is how many km from his home?
ACT Math 1.3 Intermediate Algebra 506 Views
Share It!
Description:
ACT Math Intermediate Algebra Drill 1, Problem 3. Can you find the value of a in this expression?
- Intermediate Algebra / Quadratic equations (Quadratic Formula)
- Product Type / ACT Math
- Foreign Language / Arabic Subtitled
- Foreign Language / Spanish Subtitled
- Foreign Language / Korean Subtitled
- Foreign Language / Chinese Subtitled
- Algebra / Understand the relationship between zeros and factors of polynomials
- Algebra / Understand the relationship between zeros and factors of polynomials
- Algebra / Solve equations and inequalities in one variable
- Algebra / Solve equations and inequalities in one variable
- Algebra / Solve equations and inequalities in one variable
- Algebra / Solve equations and inequalities in one variable
- Algebra / Understand the relationship between zeros and factors of polynomials
- Intermediate Algebra / Quadratic formula
Transcript
- 00:02
And here's another shmoop de jour...
- 00:04
Solve for a: 2a squared plus 4a minus 1 equals 0.
- 00:08
And here are the potential answers...
- 00:14
Before we even think about starting, we should always glance at the potential answer set first
- 00:19
Here, the numbers scream at us that the quadratic equation will be involved.
Full Transcript
- 00:23
The quadratic equation looks like this:
- 00:26
We are drawing from a line of the equation "ax squared plus bx plus c."
- 00:31
...and we have to figure out what a, b and c are so we can plug them into the right places.
- 00:37
In this case, the 2 comes from here; it's A.
- 00:39
B is here, and it's 4.
- 00:42
And C is here, and it's negative 1.
- 00:45
Now we just plug in the numbers and this is what we get.
- 00:47
Now we just have to simplify. We get negative 4 plus or minus 4 squared which is 16....
- 00:53
...minus 4 times 2, then times negative 1...
- 00:57
... so it's plus 8... and we get negative 4 plus or minus 16 plus 8, or 24, here under
- 01:02
the square root symbol...
- 01:03
...all over 2 times 2, or 4.
- 01:07
Simplify one more time and we have...
- 01:09
Both A -- here... and B -- here.
- 01:12
Answer: D.
Related Videos
ACT Math: Intermediate Algebra: Drill 3, Problem 1. Find the fifth number in the series.
ACT Math: Plane Geometry Drill 3, Problem 1. What is the area of the trapezoid shape in the video?
ACT Math: Coordinate Geometry Drill 1, Problem 1. Which inequality is expressed by the number line?
We don't like knocking people down to size, but we do like simplifying radicals. Join us?
If fleeing criminals always fled the scene of the crime at perfect right angles, it would be much easier to determine their whereabouts. Fortunatel...