2 ways
zero product property
easy way
zero product
factor perfect square
m^2-3^2=0
(m-3)(m+3)=0
set each to zero
m-3=0
x=3
m+3=0
m=-3
m=-3 or 3
easy way
add 9 to both sides
m^2=9
sqrt both sides remember to take postive and negative roots
m=+/-3
m=-3 or 3
B is answer
The equation for a parabola with directrix y = –p and focus (0, p)
The distance between vertex and directrix is P
Also the distance between vertex and focus is also P
Focus (0,p) so focus lies on y axis
Directrix line is paralled to focus point
So Directex crosses the x axis .
Hence line of symmetry lies is the y-axis.
The graph is attached below.
Teachers often all this problem a donut problem because it’s like the donut hole getting cut out of the middle. The way that you solve this is to find the area of the whole yard and subtract the area of the fountain. Since they are rectangles we’re going to use A = LW
Area of yard - Area of fountain
A = (8x)(9x) - (2x)(5x)
A = 72 x^2. - 10 x^2
A 62 x^2
So lets say that this salt and water solution consists of 100 liters.
Then that means 20 liters is salt, and 80 liters out of the 100 is water.
Now, we remove 25% of the water. 25% of 80 liters is 20 liters. So, we are left with 80-20, or 60 liters.
Now in all we have 20 liters of salt, and 60 liters of water.
The percentage of salt in the new mixture will be 20/(20+60) = 20/80 = 25%.
Your answer is 25%
