Check the picture below.
for "b", well, recall that the sum of all interior angles in a triangle is 180°.
for "a", "c" and "d", well, all those are just <u>intercepted arcs</u>.
<h3>
Answer: 15 hours (choice D)</h3>
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Work Shown:
(6 hours)/(8 trees) = (x hours)/(20 trees)
6/8 = x/20
6*20 = 8*x ... cross multiply
120 = 8x
8x = 120
x = 120/8
x = 15
It takes him 15 hours to plant 20 trees.
Answer:
b=16cm .......................
Answer:
(x, y) = (5, 1)
Step-by-step explanation:
To <em>eliminate</em> x, you can double the second equation and subtract the first.
... 2(x +4y) -(2x -3y) = 2(9) -(7)
...11y = 11 . . . . . simplify
... y = 1 . . . . . . divide by 11
Using the second equation to find x, we have ...
... x + 4·1 = 9
... x = 5 . . . . . subtract 4
_____
<u>Check</u>
2·5 -3·1 = 10 -3 = 7 . . . . agrees with the first equation
(Since we used the second equation to find x, we know it will check.)
Given:
A quadratic function has x-intercepts 2 and 6 and its vertex is (4, 8).
To find:
The corresponding quadratic expression.
Solution:
If graph of a function intersect the x-axis at c, then (x-c) is a factor of the function.
A quadratic function has x-intercepts 2 and 6. It means (x-2) and (x-6) are two factors of the required quadratic function.
The function is defined as:
...(i)
Where, a is a constant.
The vertex of the quadratic function is (4,8). It means the point (4,8) will satisfy the function.
Substituting x=4 and P(x)=8 in (i).
![8=a(4-2)(4-6)](https://tex.z-dn.net/?f=8%3Da%284-2%29%284-6%29)
![8=a(2)(-2)](https://tex.z-dn.net/?f=8%3Da%282%29%28-2%29)
![8=-4a](https://tex.z-dn.net/?f=8%3D-4a)
Divide both sides by -4.
![\dfrac{8}{-4}=a](https://tex.z-dn.net/?f=%5Cdfrac%7B8%7D%7B-4%7D%3Da)
![-2=a](https://tex.z-dn.net/?f=-2%3Da)
Putting
in (i), we get
![P(x)=-2(x-2)(x-6)](https://tex.z-dn.net/?f=P%28x%29%3D-2%28x-2%29%28x-6%29)
![P(x)=-2(x^2-6x-2x+12)](https://tex.z-dn.net/?f=P%28x%29%3D-2%28x%5E2-6x-2x%2B12%29)
![P(x)=-2(x^2-8x+12)](https://tex.z-dn.net/?f=P%28x%29%3D-2%28x%5E2-8x%2B12%29)
![P(x)=-2x^2+16x-24](https://tex.z-dn.net/?f=P%28x%29%3D-2x%5E2%2B16x-24)
Therefore, the correct option is B.