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3 years ago

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Which of the equations are true identities? \begin{aligned} \text{A. }&(y+6)(y-7)+42=y^2-y \\\\ \text{B. }&(x+3)(x-8)=x^

2-5x \end{aligned} A. B. (y+6)(y−7)+42=y 2 −y (x+3)(x−8)=x 2 −5x

2 answers:

BaLLatris [955]3 years ago

8 0

Answer:

its only A

Step-by-step explanation:

got it from khan academy

musickatia [10]3 years ago

5 0

Answer:

Only A, the first equation is true.

Step-by-step explanation:

A. (y + 6)(y – 7) + 42 = y² + 6y –7y – 42 + 42 = y² – y. This means A is true

B. (x + 3)(X – 8) = x² + 3x – 8x – 24 = x² – 5x – 24. This means B is false.

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A jumping spider's movement is modeled by a parabola. The spider makes a single jump from the origin and reaches a maximum heigh

Stella [2.4K]

A parabola is a mirror-symmetrical U-shape.

The equation of the parabola is $\mathbf{y = -\frac{1}{640}(x - 80)^2 + 10}$
The focus is $\mathbf{Focus = (80, -1760)}$
The directrix is $\mathbf{y = \frac{1}{640}}$
The axis of the symmetry of parabola is: $\mathbf{x = 80}$

From the question, we have:

$\mathbf{Vertex: (h,k) = (80,10)}$

$\mathbf{Origin: (x,y) = (0,0)}$

The equation of a parabola is:

$\mathbf{y = a(x - h)^2 + k}$

Substitute the values of origin and vertex in $\mathbf{y = a(x - h)^2 + k}$

$\mathbf{0 = a(0 - 80)^2 + 10}$

$\mathbf{0 = a(- 80)^2 + 10}$

$\mathbf{0 = 6400a + 10}$

Collect like terms

$\mathbf{6400a =- 10}$

Solve for a

$\mathbf{a =- \frac{1}{640}}$

Substitute the values of a and the vertex in $\mathbf{y = a(x - h)^2 + k}$

$\mathbf{y = -\frac{1}{640}(x - 80)^2 + 10}$

The focus of a parabola is:

$\mathbf{Focus = (h, \frac{k+1}{4a})}$

Substitute the values of a and the vertex in $\mathbf{Focus = (h, \frac{k+1}{4a})}$

$\mathbf{Focus = (80, \frac{10+1}{4 \times -\frac{1}{640}})}$

$\mathbf{Focus = (80, -\frac{11}{\frac{1}{160}})}$

$\mathbf{Focus = (80, -11\times 160)}$

$\mathbf{Focus = (80, -1760)}$

The equation of the directrix is:

$\mathbf{y = -a}$

So, we have:

$\mathbf{y = \frac{1}{640}}$ ----- the directrix

The axis of symmetry is:

$\mathbf{x = -\frac{b}{2a}}$

We have:

$\mathbf{y = -\frac{1}{640}(x - 80)^2 + 10}$

Expand

$\mathbf{y = -\frac{1}{640}(x^2 -160x + 6400) +10}$

Expand

$\mathbf{y = -\frac{1}{640}x^2 +\frac{1}{4}x - 10 +10}$

$\mathbf{y = -\frac{1}{640}x^2 +\frac{1}{4}x }$

A quadratic function is represented as:

$\mathbf{y = ax^2 + bx + c}$

So, we have:

$\mathbf{a = -\frac{1}{640}}$

$\mathbf{b = \frac{1}{4}}$

Recall that:

$\mathbf{x = -\frac{b}{2a}}$

So, we have:

$\mathbf{x = -\frac{1/4}{2 \times -1/640}}$

$\mathbf{x = \frac{1/4}{1/320}}$

This gives

$\mathbf{x = \frac{320}{4}}$

$\mathbf{x = 80}$

Hence, the axis of the symmetry of parabola is: $\mathbf{x = 80}$

Read more about parabola at:

brainly.com/question/21685473

6 0

3 years ago

X divided by 8=1.5 divided by 2<br><br> solve for "x"

Travka [436]

1. 1,5 divided by 2 is 0,75 so on the right side its 0,75

2. We make x/8 = 0,75 | *8

so we get: x = 0,75 * 8

which is the same as x = 6

so the answer is x = 6

8 0

2 years ago

Read 2 more answers

What is the axis of symmetry of the function f(x)=-(x+9)(x-21)

Firlakuza [10]

Carry out the mult.: f(x) = -[x^2 - 21x + 9x - 189]

Combine like terms: f(x) = -[x^2 - 12x - 189]
Eliminate the brackets [ ]: f(x) = -x^2 + 12x + 189
Identify coefficients a, b and c: a= -1, b=12, c=189

The equation of the axis of symmetry is x = -b/(2a), which here equals

x = -(12)/[2(-1)], or x = 6

This is also the x-coordinate of the vertex. Plug x=6 into the original equation to calculate the y-coordinate.

3 0

3 years ago

If you don’t know then don’t say anything.

tino4ka555 [31]

Answer:

in total there are 80 subjects. I don't know what class width is though.

Step-by-step explanation:

Look at the graph

3 0

3 years ago

The amount of money you earn varies directly to the number of pizzas you sell. If you earn $44 for selling 8 pizzas, How many pi

Anna [14]

Answer:

You would need to sell 24 pizzas

Step-by-step explanation

132/44= 3

Take the 3 and times it by 8

3 x 8 = 24

You would need to make 24 pizzas

Each pizza is 5.50$

So an equation for this could be

5.50x P = C

P = Pizza

and C is the cash you earned

I hope this helps

5 0

3 years ago