Step-by-step explanation:
Assuming the speed of car B to be x and the speed of car A to be x+20
<u>1</u><u>5</u><u>6</u> = <u>2</u><u>0</u><u>8</u>
x. x+20
156(x+20)= 208x
156x+3120=208x
3120=208x-156x
3120=52x
x=60
The speed of car A is (x)= 60
The speed of car B is(x+20)= 80
This seems disgusting to solve directly, so let's convert this to vertex form.
1) Divide all terms by 1/2:
2y = -x² - 4x + 14
2) Complete the square:
2y = -(x² + 4x - 14)
2y = -(x² + 4x + 4 - 4 - 14)
2y = -[(x + 2)² - 18]
2y = -(x + 2)² + 18
3) Rewrite in vertex form:
(x + 2)² = -2y + 18
(x + 2)² = -2(y - 9)
Now, we know the vertex is at (-2, 9)
It's a concave down parabola
The axis of symmetry is simply the x-ordinate of the vertex.
The focus is at (-2, 17/2)
The directrix is at (-2, 19/2)
The y-intercept is at y = 7
28.) -3 | r + 4| = -21...divide both sides by -3
| r + 4 | = -21/-3
| r + 4 | = 7
r + 4 = 7 -(r + 4) = 7
r = 7 - 4 -r - 4 = 7
r = 3 -r = 7 + 4
-r = 11
r = -11
solution is : r = 3 or r = -11
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32. ) 4| 7y + 2 | - 8 = -7....add 8 to both sides
4 | 7y + 2 | = -7 + 8
4| 7y + 2 | = 1 ...divide both sides by 4
| 7y + 2 | = 1/4
7y + 2 = 1/4 -(7y + 2) = 1/4
7y = 1/4 - 2 -7y - 2 = 1/4
7y = 1/4 - 8/4 -7y = 1/4 + 2
7y = -7/4 -7y = 1/4 + 8/4
y = -7/4 * 1/7 - 7y = 9/4
y = - 7/28 reduces to - 1/4 y = 9/4 * -1/7
y = - 9/28
solution is : y = -1/4 or y = -9/28
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34.) I cant see this one
Answer:
No
Step-by-step explanation:
-2 is closer to zero than -2.25, which means -2 is greater than -2.25
