91Ó°ÊÓ

$x^3-4x+2=0$

The slope of a vertical line is ________ ; the slope of a horizontal line is _______.

An equilateral triangle is one in which all three sides are of equal length. If two vertices of an equilateral triangle are (0, 4) and (0, 0), find the third vertex. How many of these triangles are possible?

In Problems 101–104, find the length of each side of the triangle determined by the three points P1 , P2 , and P3 . State whether the triangle is an isosceles triangle, a right triangle, neither of these, or both. (An isosceles triangle is one in which at least two of the sides are of equal length.)

$P_1=\left(2,1\right),P_2=\left(-4,1\right),P_3=\left(-4,-3\right)$

Little League Baseball Refer to Problem 106. Overlay a rectangular coordinate system on a Little League baseball diamond so that the origin is at home plate, the positive

x-axis lies in the direction from home plate to first base, and the positive y-axis lies in the direction from home plate to third base.

(a) What are the coordinates of first base, second base, and third base? Use feet as the unit of measurement.

(b) If the right fielder is located at (180, 20), how far is it from there to second base?

(c) If the center fielder is located at (220, 220), how far is it from there to third base?

True or False The point $(-1,4)$lies in quadrant IV of the Cartesian plane.

Use slopes to show that the quadrilateral whose vertices are $(1,-1),(4,1),(2,2)$and $(5,4)$is a parallelogram.

True or False The midpoint of a line segment is found by averaging the x-coordinates and averaging the y-coordinates of the endpoints.

Florida Power & Light Company supplies electricity to residential customers for a monthly customer charge of $5.90 plus 8.81 cents per kilowatt-hour for up to 1000 kilowatt-hours.

(a) Write a linear equation that relates the monthly charge C, in dollars, to the number x of kilowatt hours used in a month,$0≤x≤1000$

(b) Graph this equation.

(c) What is the monthly charge for using 200 kilowatthours?

(d) What is the monthly charge for using 500 kilowatthours?

(e) Interpret the slope of the line.

The relationship between Celsius (°C) and Fahrenheit (°F) degrees of measuring temperature is linear. Find a linear equation relating °C and °F if 0°C corresponds to 32°F and 100°C corresponds to 212°F. Use the equation to find the Celsius measure of 70°F.