Answer:
90 degrees
Step-by-step explanation:
Is that supposed to be x² -4x -5 = 0 or x²-4-5=0 as written? We'll do both.
As written it's
x²=9 so x=±3, no quadratic formula required.
Let's assume you meant
x² -4x - 5 = 0
So much temptation. This factors as
(x-5)(x+1)=0 so roots x=5, x=-1. But that didn't use the quadratic formula..
There's a shortcut to the quadratic formula called the Shakespeare Quadratic Formula (2b or -2b) that's useful when the linear term is even.
In that case x²-2bx+c has zeros at z=b±√(b²-c)
x = 2 ± √(4 - -5) = 2 ± √9 = 2 ± 3 = { -1 , 5 }
OK, let's do it like they want
x² - 4x - 5 = 0
We have a=1, b=-4, c=-5 and the quadratic formula
![x=\dfrac{-b \pm \sqrt{b^2-4ac}}{2a}](https://tex.z-dn.net/?f=x%3D%5Cdfrac%7B-b%20%5Cpm%20%5Csqrt%7Bb%5E2-4ac%7D%7D%7B2a%7D)
![x = \dfrac{-(-4) \pm \sqrt{(-4)^2-4(1)(-5)}}{2(1)} = \frac 1 2 (4 \pm \sqrt{36}) = \frac 1 2 (4 \pm 6) = \{-1, 5\}](https://tex.z-dn.net/?f=x%20%3D%20%5Cdfrac%7B-%28-4%29%20%5Cpm%20%5Csqrt%7B%28-4%29%5E2-4%281%29%28-5%29%7D%7D%7B2%281%29%7D%20%3D%20%5Cfrac%201%202%20%284%20%5Cpm%20%5Csqrt%7B36%7D%29%20%3D%20%5Cfrac%201%202%20%284%20%5Cpm%206%29%20%3D%20%5C%7B-1%2C%205%5C%7D)
Answer: x=-1 or x=5
Answer:
could you show a picture
Step-by-step explanation:
please then i could answer
Just write 5-8i and then replace the - sign with the + sign: 5+8i.
Answer:
69.1 cm (nearest tenth)
Step-by-step explanation:
Circumference of circle= 2πr, where r is the radius.
Given that r= 11 cm,
circumference of the circle
= 2(π)(11)
= 22π
= 69.1 cm (nearest tenth)