3 months ago Santos could walk 2 miles in 40 min. today he can walk 2 miles in 25 min. find percent of change

Solving quadratic equations with complex solutions x2 + 4x + 8 = 0.

Daniel [21]

Answer:

$\large\boxed{x=-2\pm2i}$

Step-by-step explanation:

$x^2+4x+8=0\qquad\text{subtract 8 from both sides}\\\\x^2+4x+8-8=0-8\\\\x^2+2(x)(2)=-8\qquad\text{add}\ 2^2\ \text{to both sides}\\\\x^2+2(x)(2)+2^2=-8+2^2\qquad\text{use}\ (a+b)^2=a^2+2ab+b^2\\\\(x+2)^2=-8+4\\\\(x+2)^2=-4\iff x+2=\pm\sqrt{-4}\\\\x+2=\pm\sqrt{(4)(-1)}\qquad\text{use}\ \sqrt{ab}=\sqrt{a}\cdot\sqrt{b}\\\\x+2=\pm\sqrt4\cdot\sqrt{-1}\qquad\text{use}\ \sqrt{-1}=i\\\\x+2=\pm2\cdot i\qquad\text{subtract 2 from both sides}\\\\x=-2\pm2i$

4 0

3 years ago

Find the circumference and the area of a circle with radius 3 m.

Effectus [21]

Answer:

$\boxed {c= 18.84 \ m}$

$\boxed {a=28.26 \ m^2}$

Step-by-step explanation:

We are asked to find the circumference and area of a circle with a radius of 3 meters.

<h3>1. Circumference </h3>

The circumference is the perimeter of a circle. It is calculated using the following formula:

$c= \pi d$

We know the radius of the circle is 3 meters, but we must find the radius. The radius is the line from the center to the circle's edge, while the diameter is the line through the center from edge to edge. Therefore, the diameter is twice the radius.

d= 2 r
d= 2 * 3 m
d= 6 m

The diameter is 6 meters and we are using 3.14 for pi. Substitute these values into the circumference formula.

$c= (3.14)(6 \ m )$

Multiply.

$\bold {c= 18.84 \ m}$

The area is the size of the circle's surface. It is calculated using the following formula.

$a= \pi r^2$

The radius is 3 meters are we are using 3.14 for pi. Substitute these values into the area formula.

$a= (3.14)(3 \ m)^2$

Solve the exponent.

(3 m)² = (3 m)(3 m)= 9 m²

$a= (3.14)(9 \ m)^2$

$\bold {a=28.26 \ m^2}$

The circumference is 18.84 meters and the area is 28.26 square meters.

6 0

3 years ago

How do you think inequalities are different from equations you have worked with before?

dmitriy555 [2]

Answer:

Inequalities are different from equations. If you multiply or divide both sides of an equation by the same negative number, the equation remains the same, but If you multiply or divide both sides of an inequality by the same negative number, the inequality reverses.

4 0

3 years ago

1. How many fifties are there in one hundred thousand?

VladimirAG [237]

There are 2,000 fifties in one hundred thousand

7 0

2 years ago

What % could i make 2/5 of a hour? like 10% of a hour. like that.

yarga [219]

well, we can say that 1 hour is 100%, what is 2/5 hr off of it in percentage?

$\begin{array}{ccll} hour&\%\\ \cline{1-2} 1 & 100\\ \frac{2}{5}& x \end{array} \implies \cfrac{1}{~~ \frac{2}{5}~~}=\cfrac{100}{x}\implies \cfrac{5}{2}=\cfrac{100}{x} \\\\\\ 5x=200\implies x=\cfrac{200}{5}\implies x=40$

7 0

3 years ago