X^2 -61 =20
X^2= 81x =9 x=-9
Answer:
Step-by-step explanation:
Get the perimeter of the each shape and add it all up to get the total fencing material required.
2 square flower beds = 2 x 4a = 8a
1 rectangular play ground = 2l + 2w
total fencing material = 8a + 2l + 2w
48 cm is the area because 12x4 is 48.
Plotting the points could help you notice that they lie along a parabola. In particular, you can see that 
is always 4 more than 
.
So, the relation is
We have 10 ml of 20% acid to which we need to add "x" milliliters of 100% acid to make 50% acid.
.20 * 10 + 1.00x = .50 * (10 +x)
in which "x" is the volume of the 100% acid to be added.
2 + x = 5 + .5 x
.5x = 3
x = 6 milliliters
Source:
http://www.1728.org/mixture.htm
Scroll down to problem B
