Question 21
Let's complete the square
y = 3x^2 + 6x + 5
y-5 = 3x^2 + 6x
y - 5 = 3(x^2 + 2x)
y - 5 = 3(x^2 + 2x + 1 - 1)
y - 5 = 3(x^2+2x+1) - 3
y - 5 = 3(x+1)^2 - 3
y = 3(x+1)^2 - 3 + 5
y = 3(x+1)^2 + 2
Answer: Choice D
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Question 22
Through trial and error you should find that choice D is the answer
Basically you plug in each of the given answer choices and see which results in a true statement.
For instance, with choice A we have
y < -4(x+1)^2 - 3
-7 < -4(0+1)^2 - 3
-7 < -7
which is false, so we eliminate choice A
Choice D is the answer because
y < -4(x+1)^2 - 3
-9 < -4(-2+1)^2 - 3
-9 < -7
which is true since -9 is to the left of -7 on the number line.
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Question 25
Answer: Choice B
Explanation:
The quantity (x-4)^2 is always positive regardless of what you pick for x. This is because we are squaring the (x-4). Squaring a negative leads to a positive. Eg: (-4)^2 = 16
Adding on a positive to (x-4)^2 makes the result even more positive. Therefore (x-4)^2 + 1 > 0 is true for any real number x.
Visually this means all solutions of y > (x-4)^2 + 1 reside in quadrants 1 and 2, which are above the x axis.
There are two terms since 3x is a term, and 5 is a term.
Answer:
x = - 2 or x = 5
Step-by-step explanation:
Given
3x² - 9x - 30 = 0 ← in standard form
Divide all terms by 3
x² - 3x - 10 = 0
To factor the quadratic
Consider the factors of the constant term (- 10) which sum to give the coefficient of the x- term (- 3)
The factors are - 5 and + 2, since
- 5 × 2 = - 10 and - 5 + 2 = - 3, thus
x² - 3x - 10 = 0
(x - 5)(x + 2) = 0
Equate each factor to zero and solve for x
x - 5 = 0 ⇒ x = 5
x + 2 = 0 ⇒ x = - 2
The solution of the system can be x - 3y = 4 only if both the equations can be simplified to x - 3y = 4.
This will mean that both the equations will result in the same line which is x - 3y = 4 and thus have infinitely many solutions.
Second equation is:
Qx - 6y = 8
Taking 2 common we get:
(Q/2)x - 3y = 4
Comparing this equation to x- 3y = 4, we can say that
Q/2 = 1
So,
Q = 2
Therefore, the second equation will be:
2x - 6y = 8
