Answer this quadratic word problems? please!

Let x and x+2 be the number
A/q
x+x+2=40
2x=38
x=38/2
so,x=19
hence 19 and 21 are two number

Q1.

First of all, you don't have to use quadratic equations to solve this.
"Two consecutive odd integers whose sum is 40" is sufficient, because you can intuitively see that one must be one less than half of 40, which is 19, and the other must be one more than half of 40, which is 21. If you want to use algebra to solve it, you can do this:

x + (x + 2) = 40
2x + 2 = 40
2x = 38
x = 19
x + 2 = 21

If you want to solve it using the "Two consecutive odd integers whose product is 399" piece of information, you'll have to use quadratic equations:

x (x + 2) = 399
x^2 + 2x = 399
x^2 + 2x - 399 = 0
(x + 21)(x - 19) = 0
x + 21 = 0 or x - 19 = 0
x = -21 or x = 19
And therefore x + 2 = -19 or x + 2 = 21.
So the two possible pairs of consecutive odd numbers with a product of 399 are -19 and -21, or 19 and 21. But since you know that the sum is 40 rather than -40, the correct pair must be 19 and 21.


Q2.
If the area of the square garden is 1764 square feet, then the length of each side is sqrt(1764) feet, which is 42 feet. The sprinkler spray needs to reach from the center of the square to the corners, which are the farthest points from the center, which is an offset of 21 feet in one axis and 21 feet in the perpendicular axis. Use the distance formula d = sqrt((delta_x)^2 + (delta_y)^2), and you'll get:

d = sqrt(21^2 + 21^2)
d = sqrt(441 + 441)
d = sqrt(441 * 2)
d = sqrt(441) * sqrt(2)
d = 21 sqrt(2)
The decimal approximation is 29.70 feet, or 29 feet and 8.4 inches.

Q3.
Since the squares that you're cutting from each corner are one foot on each side, the height of the box will be one feet when you fold up the sides. Therefore, for a volume of 25 cubic feet, the box is 25 square feet by one foot high. Because it's a square, each side is sqrt(25) feet, or 5 feet. So the box is 5 feet by 5 feet by 1 foot. However, that's after folding the one-foot sides up. Before folding, the cardboard was a flat piece with dimensions of 7 feet by 7 feet.