How to find length in quadratic equation of right angle triangle?

1 answer:

8 0

If you have an equation you are factoring to find the length of a leg of a right triangle, factor it to solve for x. If by some chance, one of those x-values is negative we can count that one out since length will never be negative. If you have 2 positive solutions, you may have to use some math to see if both of the lengths work according to pythagorean's theorem or if only one works. It depends upon what type of information you are given other than the quadratic.

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PLS HELP ILL GIVE BRAINLIEST

inysia [295]

<h3>Answer: 14x - 8</h3>

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Explanation:

I'll use the quadratic formula to find the roots or x intercepts. This slight detour allows us to factor without having to use guess-and-check methods.

The equation is of the form ax^2+bx+c = 0

a = 12
b = -11
c = -5

This leads to...

$x = \frac{-b\pm\sqrt{b^2-4ac}}{2a}\\\\x = \frac{-(-11)\pm\sqrt{(-11)^2-4(12)(-5)}}{2(12)}\\\\x = \frac{11\pm\sqrt{361}}{24}\\\\x = \frac{11\pm19}{24}\\\\x = \frac{11+19}{24} \ \text{ or } \ x = \frac{11-19}{24}\\\\x = \frac{30}{24} \ \text{ or } \ x = \frac{-8}{24}\\\\x = \frac{5}{4} \ \text{ or } \ x = -\frac{1}{3}$

Now use those roots to form these steps

$x = \frac{5}{4} \ \text{ or } \ x = -\frac{1}{3}\\\\4x = 5 \ \text{ or } \ 3x = -1\\\\4x - 5 =0 \ \text{ or } \ 3x+1 = 0\\\\(4x-5)(3x+1) = 0$

Refer to the zero product property for more info.

Therefore, the original expression factors fully to (4x-5)(3x+1)

Use the FOIL rule to expand it out and you should get 12x^2-11x-5 again.

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We did that factoring so we could find the side lengths of the rectangle.

I'm using the fact that area = length*width

L = length = 4x-5
W = width = 3x+1

The order of length and width doesn't matter.

From here, we can then compute the perimeter of the rectangle

P = 2(L+W)

P = 2(4x-5+3x+1)

P = 2(7x-4)

P = 14x - 8

6 0

2 years ago

Jane has $5 more than three times as much money as Lonnie has.Bob has $1 less than four times as much money as Lonnie has. All t

kkurt [141]

Starting equation:
92=J+L+B

To find how much money Jane has, we use the equation:
J=5+3L
To find how much money Bob has, we use the equation:
B=4L-1

Enter those equations in the problem

92=(5+3L)+L+(4L-1)
Combine like terms
92=4+8L
Subtract 4 to isolate variable
88=8L
Divide by 8 to isolate variable
11=L

Answer:
Lonnie has $11
Jane has $38
Bob has $43

side note: Lonnie is that one poor friend we all have

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