ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Math II Videos 98 videos
ACT Math Pre-Algebra: Drill 3, Problem 4. Find the solution to this equation.
Elementary Algebra: Drill 4, Problem 1. Simplify the expression.
ACT Math Intermediate Algebra Drill 2, Problem 2. How else can the expression be written?
ACT Math 2.5 Elementary Algebra 286 Views
Share It!
Description:
ACT Math Section: Elementary Algebra Drill 2, Problem 5. Use these two equations to solve for both x and y.
- Elementary Algebra / Linear equations
- Product Type / ACT Math
- Foreign Language / Arabic Subtitled
- Foreign Language / Korean Subtitled
- Foreign Language / Spanish Subtitled
- Foreign Language / Chinese Subtitled
- Algebra / Solve systems of equations
- Algebra / Solve systems of equations
- Algebra / Solve systems of equations
- Algebra / Solve systems of equations
- Elementary Algebra / Evaluation of algebraic expressions through substitution
Transcript
- 00:02
Here's your shmoop du jour:
- 00:05
Solve for x and y: 3x + 2y = 13 6x + y = 20
- 00:11
And here are the potential answers...
- 00:20
OK. Not much of a brain-squeezer.
- 00:23
Since y, stands alone in the bottom equation, let's solve for y.
Full Transcript
- 00:27
We get y equals 20 minus 6x.
- 00:30
Now we just substitute 20 minus 6x anywhere we see a y.
- 00:34
Ok so rewrite the above equation with that substitution and we have
- 00:37
3x plus 40 minus 12x equals 13
- 00:41
Simplify to get negative 9x equals 13 minus 40 or negative 9x equals negative 27; divide
- 00:48
both sides by negative 9 and we get x equals 3.
- 00:52
Phew. Great. Only A and B are possible answers.
- 00:55
Now just plug in 3 for x in the second equation
- 00:58
and we get 6 times 3 is 18... plus y... equals 20.
- 01:02
Now subtract 18 from both sides and we get y equals 2.
- 01:06
Here we go. So boom! The answer is B.
Related Videos
ACT Math: Coordinate Geometry Drill 1, Problem 1. Which inequality is expressed by the number line?
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?
You don't want to leave a bunch of unsolved rational equations sitting around.
Solving inequalities using blob fish? Yes, please!