Answer: 12.75 inches
Step-by-step explanation:
Let x represent last year's rainfall.
Multiply by 0.8 since this year was 20% less.
x(0.8)= 10.2
x = 12.75
"Completing the square" is the process used to derive the quadratic formula for the general quadratic ax^2+bx+c=0. Suppose you did not know the value of a,b, or c of the quadratic...
ax^2+bx+c=0 You need a leading coefficient of one for the process to work, so you divide the whole equation by a
x^2+bx/a+c/a=0 now you move the constant to the other side of the equation
x^2+bx/a=-c/a now you halve the linear coefficient, square that, then add that value to both sides, ie, (b/(2a))^2=b^2/(4a^2)...
x^2+bx/a+b^2/(4a^2)=b^2/(4a^2)-c/a now the left side is a perfect square...
(x+b/(2a))^2=(b^2-4ac)/(4a^2) now take the square root of both sides
x+b/(2a)=±√(b^2-4ac)/(2a) now subtract b/(2a) from both sides
x=(-b±√(b^2-4ac))/(2a)
It is actually much simpler keeping track of everything when using known values for a,b, and c, but the above explains the actual process used to create the quadratic formula, which the above solution is. :)
Answer:
120 ounces
Step-by-step explanation:
First find how many ft2 of lawn 1 once can seed.
To do this we simply divide 3000 by 50 ( because 50 ounces of grass seed can seed 3000 ft2 of lawn )
3000 / 50 = 60
So 1 ounce can seed 60ft2 of lawn
To find how many ounces would be needed to seed 7200 ft2 of lawn we would divide 7200 by the amount of lawn 1 once can seed ( which is 60ft2 )
7200/60 = 120
So 120 ounces of grass seed would be needed to seed 7200 ft2 of lawn
