QUESTION IMAGE
Question
1 identify and factor the difference of two perfect squares.
2 look at the expression below.
$-4x^2 + 16x - 24 + 6x$
which of the following cannot be a pair of factors of the expression?
a. $-2, x - 3$
b. $-2, 2x - 3$
c. $2, 4 - x$
d. $2, 2x - 3$
3 michelle factored $x^2 - 6x + 9$ as follows:
$x^2 - 6x + 9 =$
$x^2 - 2(x \cdot 3) + 3^2 =$
$(x - 3)(x + 3)$
the correct factorization should be:
a. $(x - 3)(x + 3)$
b. $(x + 3)^2$
c. $(x - 3)^2$
4 which of these statements accurately describes the graph of the function $f(x) = x^2 + 20x + 100$ ?
a. the graph passes through the x-axis at -10.
b. the graph passes through the x-axis at 10.
c. the graph passes through the y-axis at -10.
d. the graph passes through the y-axis at 10.
Question 2
Step1: Simplify the expression
First, combine like terms in \(-4x^2 + 16x - 24 + 6x\). The like terms for \(x\) are \(16x\) and \(6x\), so adding them gives \(22x\). The expression becomes \(-4x^2 + 22x - 24\). We can factor out a \(-2\) (or \(2\)) to simplify. Factoring out \(-2\): \(-2(2x^2 - 11x + 12)\)? Wait, no, let's check again. Wait, original expression: \(-4x^2 + 16x + 6x - 24 = -4x^2 + 22x - 24\). Alternatively, factor out \(-2\): \(-2(2x^2 - 11x + 12)\)? Wait, maybe I made a mistake. Wait, let's factor out \(-2\) from all terms: \(-2(2x^2 - 11x + 12)\)? No, wait, \(-4x^2\div(-2)=2x^2\), \(22x\div(-2)= -11x\), \(-24\div(-2)=12\). Alternatively, factor out \(2\): \(2(-2x^2 + 11x - 12)\). Wait, maybe another approach. Let's factor the original expression. Let's first write it as \(-4x^2 + 22x - 24\). Multiply numerator and denominator by \(-1\) to make the leading coefficient positive: \(4x^2 - 22x + 24\). Now, factor this quadratic. The discriminant is \(22^2 - 4\times4\times24 = 484 - 384 = 100\). So roots are \(\frac{22\pm10}{8}\), so \(\frac{32}{8}=4\) and \(\frac{12}{8}=\frac{3}{2}\). So \(4x^2 -22x +24 = (4x - 6)(x - 4)\) (wait, no, using factoring: \(4x^2 -22x +24 = 2(2x^2 -11x +12)\), and \(2x^2 -11x +12\) factors as \((2x - 3)(x - 4)\)? Wait, \((2x - 3)(x - 4)=2x^2 -8x -3x +12=2x^2 -11x +12\). Yes. So going back, the original expression \(-4x^2 +22x -24 = -2(2x^2 -11x +12)= -2(2x - 3)(x - 4)\). Alternatively, we can write it as \(2(-2x + 3)(x - 4)\) or \(2(3 - 2x)(x - 4)\) or \(2(2x - 3)(4 - x)\) (since \((x - 4)= - (4 - x)\), so \(-2(2x - 3)(x - 4)=2(2x - 3)(4 - x)\)). Now let's check each option:
- Option A: \(-2\) and \(x - 3\). Let's multiply \(-2(x - 3)= -2x +6\). Does this divide into the original expression? Let's see, original expression is \(-4x^2 +22x -24\). If we divide \(-4x^2 +22x -24\) by \(-2(x - 3)= -2x +6\), let's perform polynomial division. Dividend: \(-4x^2 +22x -24\), divisor: \(-2x +6\). Multiply divisor by \(2x\): \(-4x^2 +12x\). Subtract from dividend: \((-4x^2 +22x -24) - (-4x^2 +12x)=10x -24\). Now, divide \(10x -24\) by \(-2x +6\). Multiply divisor by \(-5\): \(10x -30\). Subtract: \((10x -24)-(10x -30)=6\). So there's a remainder, but wait, maybe I made a mistake. Wait, earlier factoring showed the expression is \(2(2x - 3)(4 - x)\) or \(-2(2x - 3)(x - 4)\). Let's check option B: \(-2\) and \(2x - 3\). Multiply \(-2(2x - 3)= -4x +6\). Divide original expression \(-4x^2 +22x -24\) by \(-4x +6\). Dividend: \(-4x^2 +22x -24\), divisor: \(-4x +6\). Multiply divisor by \(x\): \(-4x^2 +6x\). Subtract: \((-4x^2 +22x -24)-(-4x^2 +6x)=16x -24\). Multiply divisor by \(-4\): \(16x -24\). Subtract: \(0\). So it factors as \((-4x +6)(x - 4)= -2(2x - 3)(x - 4)\), which matches. Option C: \(2\) and \(4 - x\). Multiply \(2(4 - x)=8 - 2x\). Divide original expression \(-4x^2 +22x -24\) by \(8 - 2x\) (which is \(-2(x - 4)\)). So dividing by \(-2(x - 4)\) is same as multiplying by \(-1/(2(x - 4))\). Wait, original expression is \(-2(2x - 3)(x - 4)\), so \(2(4 - x)=2(-(x - 4))= -2(x - 4)\). So \(-2(2x - 3)(x - 4)= (2(4 - x))(2x - 3)\), since \(-2(x - 4)=2(4 - x)\). So that works. Option D: \(2\) and \(2x - 3\). Multiply \(2(2x - 3)=4x - 6\). Divide original expression \(-4x^2 +22x -24\) by \(4x - 6\). Dividend: \(-4x^2 +22x -24\), divisor: \(4x - 6\). Multiply divisor by \(-x\): \(-4x^2 +6x\). Subtract: \((-4x^2 +22x -24)-(-4x^2 +6x)=16x -24\). Now, divide \(16x -24\) by \(4x - 6\). Multiply divisor by \(4\): \(16x -24\). Subtract: \(0\). Wait, but earlier we had the expression as \(-2(2x - 3)(x - 4)\), a…
Step1: Recall the perfect square trinomial formula
The perfect square trinomial formula is \(a^2 - 2ab + b^2 = (a - b)^2\) and \(a^2 + 2ab + b^2 = (a + b)^2\). For the expression \(x^2 - 6x + 9\), we can identify \(a = x\) and \(b = 3\) because \(x^2 = a^2\), \(9 = b^2\), and \(-6x = -2 \times x \times 3\) (which is \(-2ab\)).
Step2: Apply the formula
Using the formula \(a^2 - 2ab + b^2 = (a - b)^2\), substituting \(a = x\) and \(b = 3\), we get \((x - 3)^2\). Michelle incorrectly used the difference of squares formula \((a - b)(a + b) = a^2 - b^2\), which is for the difference of two squares, not a perfect square trinomial.
Step1: Factor the quadratic function
The function \(f(x) = x^2 + 20x + 100\) is a perfect square trinomial. Using the formula \(a^2 + 2ab + b^2 = (a + b)^2\), we identify \(a = x\) and \(b = 10\) (since \(x^2 = a^2\), \(100 = b^2\), and \(20x = 2 \times x \times 10\) (which is \(2ab\))). So \(f(x) = (x + 10)^2\).
Step2: Analyze the x-intercept and y-intercept
- X-intercept: The x-intercept occurs where \(f(x) = 0\). So \((x + 10)^2 = 0\) implies \(x + 10 = 0\) → \(x = -10\). So the graph touches the x-axis at \(x = -10\) (a repeated root).
- Y-intercept: The y-intercept occurs where \(x = 0\). Substitute \(x = 0\) into \(f(x)\): \(f(0) = 0^2 + 20(0) + 100 = 100\). So the graph passes through the y-axis at \(100\), not \(-10\) or \(10\).
Now, check the options:
- Option A: The graph passes through the x-axis at \(-10\). This is correct because the root is \(x = -10\) (a repeated root, so it touches the x-axis here).
- Option B: The graph passes through the x-axis at \(10\). Incorrect, since the root is \(-10\).
- Option C: The graph passes through the y-axis at \(-10\).
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A. \(-2\), \(x - 3\)