Answer:
Step-by-step explanation:
Quadratic function-
It is a function that can be represented by an equation of the form 
, where 
In a quadratic function, the greatest power of the variable is 2.
As in the first option the highest power is 3, so it is not a quadratic function.
Even though the power of x is 2 in the third option, but as it is in the denominator, so the overall power of x becomes -2. Hence it is not a quadratic function.
As the coefficient of 
is 0 in case of fourth option, so it is not a quadratic function.
Equation in option 2 satisfies all the conditions of quadratic function, hence it is the quadratic function.
angle AOB = 132 and is also the sum of angles AOD and
DOB. Hence
angle AOD + angle DOB = 132° ---> 1
angle COD = 141 and is also the sum of angles COB and BOD. Hence
angle COB + angle DOB = 141° ---> 2
Now we add the left sides together and the right sides of equations 1 and 2
together to form a new equation.
angle AOD + angle DOB + angle COB + angle DOB = 132 + 141 ---> 3
We should also note that:
angle AOD + angle DOB + angle COB = 180°
Therefore substituting angle AOD + angle DOB + angle COB in equation 3 by 180
and solving for angle DOB:
180 + angle DOB = 132 + 141
angle DOB = 273 - 180 = 93°
If the ratio of red marbles to blue marbles in a jar is 3 to 8, the meaning is for every 3 red marbles there are 8 blue marbles.
3 red marbles------------------8 blue marbles.
ratio=3/8
we have 40 blue marbles; we have to compute the number of red marbles.
1) Method 1; by the rule three.
3 red marbles-----------------8 blue marbles
x----------------------------------40 blue marbles
x=(3 red marbles * 40 blue marbles) / 8 blue marbles=15 red marbles.
answer: B. 15
Method 2: the ratio of red marbles to blue marbles is
ratio=number of red marbles / number of blue marbles
ratio=3/8
if we want to compute the number of red marbles we have to multiply the number of blue marbles by this ratio.
number of red marbles=ratio (red/blue)* number of blue marbles
number of red marbles=(3/8)*40=15
Answer: B.15
