Is it - or + 60 plz help me
1 answer:
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Answer:
C. x^2 + 2x - 1 = 3
Step-by-step explanation:
The standard form of a quadratic equation is
ax^2 + bx + c = 0
We need to use the quadratic formula and the given expression to find the values of a, b, and c.
The quadratic formula is
Where the formula has -b, the problem has -2, so b = 2.
Now we have
ax^2 + 2x + c = 0
In the denominator, where the formula has 2a, the problem has 2(1), so a = 1.
Now we have
x^2 + 2x + c = 0
Inside the root, the quadratic formula has -4ac. the problem shows -4(1)(-4). Since we already know that a = 1, then c = -4.
Now we have
x^2 + 2x - 4 = 0
Let's look at choice A.
x^2 + 1 = 2x - 3
Subtract 2x from both sides. Add 3 to both sides.
x^2 - 2x + 4 = 0 <em>This is not it!</em>
Let's look at choice B.
x^2 - 2x - 1 = 3
Subtract 3 from both sides.
x^2 - 2x - 4 = 0 <em>This is not it!</em>
Let's look at choice C.
x^2 + 2x - 1 = 3
Subtract 3 from both sides.
x^2 + 2x - 4 = 0 <em>This is it!</em>
Answer: C. x^2 + 2x - 1 = 3
The volume of a cuboid is given by length × width × height
We have:
Volume = 7.6 ft³
Height = 3x - 1
Length = x + 5
Width = x
Substituting these into the formula, we have:
7.6 = (3x - 1) (x + 5) (x)
7.6 = [3x² + 15x - x - 5] (x)
7.6 = [3x² + 14x - 5](x)
7.6 = 3x³ + 14x² - 5x
0 = 3x³ + 14x² - 5x - 7.6
Drawing the graph is one way of finding the solution (refer to the graph below):
We have three solutions (where the curve crosses the x-axis):
x = -4.9
x = -0.6
x = 0.8
Putting these solutions back into the context, since we are looking for the value of x which is part of measurement of length, we cannot have negative value, so we will take the value of x = 0.8 ft
Converting 0.8 ft into inches = 0.8 × 12 inches = 9.6 inches
Answer: x = 9.6 inches
We have:
Volume = 7.6 ft³
Height = 3x - 1
Length = x + 5
Width = x
Substituting these into the formula, we have:
7.6 = (3x - 1) (x + 5) (x)
7.6 = [3x² + 15x - x - 5] (x)
7.6 = [3x² + 14x - 5](x)
7.6 = 3x³ + 14x² - 5x
0 = 3x³ + 14x² - 5x - 7.6
Drawing the graph is one way of finding the solution (refer to the graph below):
We have three solutions (where the curve crosses the x-axis):
x = -4.9
x = -0.6
x = 0.8
Putting these solutions back into the context, since we are looking for the value of x which is part of measurement of length, we cannot have negative value, so we will take the value of x = 0.8 ft
Converting 0.8 ft into inches = 0.8 × 12 inches = 9.6 inches
Answer: x = 9.6 inches