Step-by-step explanation:
they're is a neat little trick.
but first of all, "roots" means the 0 solutions of the equation. like
ax² + bx + c = 0
there are 2 solutions for x to make the whole expression equal 0.
these are the "roots".
now to the little trick :
when is a multiplication resulting in 0 ?
when at least one of the factors is 0.
and any quadratic expression can be written as multiplication of 2 factors. like
c(x - a)(x - b) = cx² - cax - cbx + cab
what are the "roots" or 0 points ?
either
c = 0
x - a = 0 | x = a
x - b = 0 | x = b
the leading coefficient = 3.
that means nothing else than c = 3.
root = 1 means (x - 1) is one factor.
root = -5 means (x + 5) is the other factor.
so, we have
3(x - 1)(x + 5) = 3x² + 12x - 15
and the equation is
3x² + 12x - 15 = 0
or
3x² + 12x = 15
Answer: =(x - 1) x (x^2 + x + 1)
Let
x-------------> amount added <span>to each side
</span>A-------------> area increased----------> 84 ft²
we know that
A=(10+x)*(5+x)=84-----------> 10*5+10*x+5*x+x²
50+15x+x²=84----------> x²+15x-34=0
<span>solving the second order equation
</span>x1=-17
x2=2
the answer is x=2 ft
Answer:
Step-by-step explanation:
In rectangle ABCD, AB = 6, BC = 8, and DE = DF.
ΔDEF is one-fourth the area of rectangle ABCD.
We want to determine the length of EF.
First, we can find the area of the rectangle. Since the length AB and width BC measures 6 by 8, the area of the rectangle is:
The area of the triangle is 1/4 of this. Therefore:
The area of a triangle is half of its base times its height. The base and height of the triangle is DE and DF. Therefore:
Since DE = DF:
Thus:
Since ABCD is a rectangle, ∠D is a right angle. Then by the Pythagorean Theorem:
Therefore:
Square:
Add:
And finally, we can take the square root of both sides:
Answer:
c) The car dealer's business is expanding rapidly.
Step-by-step explanation:
You can tell because they're selling more and more every month.
