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SAT Math 1.5 Algebra and Functions. If f (x) = x2 - 16 and g(x) = x4 - 256, what is f of x divided by g of x?
ACT Math 3.4 Elementary Algebra 235 Views
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Description:
ACT Math Elementary Algebra Drill 3, Problem 4. Solve for y in this equation.
- Elementary Algebra / Solving simple quadratic equations
- Product Type / ACT Math
- Foreign Language / Arabic Subtitled
- Foreign Language / Korean Subtitled
- Foreign Language / Chinese Subtitled
- Foreign Language / Spanish Subtitled
- Algebra / Understand the relationship between zeros and factors of polynomials
- Algebra / Understand the relationship between zeros and factors of polynomials
- Algebra / Use polynomial identities to solve problem
- Algebra / Understand the relationship between zeros and factors of polynomials
- Algebra / Use polynomial identities to solve problems
- Elementary Algebra / Solve quadratic equations by factoring
Transcript
- 00:02
For a good time, solve this shmoopy question... Solve for y: 2y squared plus 7y plus 3 equals 0
- 00:10
And here are the potential answers...
- 00:15
Ok. It's just a basic factoring question. It's in the form of something squared plus something
- 00:20
plus an integer equals zero.
- 00:22
A bell should be going off when we see an equation like this.
Full Transcript
- 00:25
We just have to figure out what the factors are... and there's a bit of a curveball in
- 00:29
here in that there's a 2 on the front end.
- 00:32
So we know that one of the factors is going to be a 2, as in:
- 00:35
The quantity 2y plus something times the quantity y plus something.
- 00:38
Let's plug in some numbers to get the 3. It's kind of easy because 3 only has 2 factors:
- 00:44
1 and 3...
- 00:46
Now we have quantity 2y plus 1 times quantity y plus 3.
- 00:50
If we multiply it out, we get 2y times y here, which is 2y squared.
- 00:55
Then we have 2y times 3, which is 6y
- 00:57
plus y times 1, which is just... y.
- 01:01
6y plus y is 7y; then, 1 times 3 is just 3 so we're done.
- 01:07
But now... how do we make the whole thing equal to zero? Well, one of the elements here
- 01:11
has to BE zero.
- 01:14
If y is negative 3 then this one is 3 minus 3 which is 0...
- 01:20
...and here, it's just negative one half, because negative 1 half times 2 is negative
- 01:24
1... and negative 1 plus positive 1 is zero.
- 01:27
So the other answer is negative one half and the answer is A and C...
- 01:31
...or option E.
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