Quadratic Equations and Solutions in Standard Form
Understand and solve quadratic equations using the quadratic formula, find discriminants, and analyze solutions. Solve guided practice problems effectively.
Quadratic Equations and Solutions in Standard Form
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Presentation Transcript
Section 4.8 Notes • Read all of p. 292 until Example 1.
Examples • Solve using the quadratic formula. • 1. x2 + 3x = 2 • 2. 25x2 – 18x = 12x – 9 • 3. -x2 + 4x = 5
1. x2 + 3x = 2 • Write in standard form. • x2 + 3x – 2 = 0 a = 1 b = 3 c = -2
2. 25x2 – 18x = 12x – 9 • Write in standard form. • 25x2 − 30x + 9 = 0 a = 25 b = -30 c = 9
3. -x2 + 4x = 5 • Write in standard form. • -x2 + 4x – 5 = 0 a = -1 b = 4 c = -5 Do Guided Practice #1 to #3. Read p. 294 until Example 4.
Example 4 • Find the discriminant of the quadratic equation and give the number and type of solutions of the equation. • a. x2 – 8x + 17 = 0 • b. x2 – 8x + 16 = 0 • c. x2 – 8x + 15 = 0
a. x2 – 8x + 17 = 0 a = 1 b = -8 c = 17 Two imaginary solutions
b. x2 – 8x + 16 = 0 a = 1 b = -8 c = 16 One real solution
b. x2 – 8x + 15 = 0 a = 1 b = -8 c = 15 Two real solutions Do Guided Practice #4 and #8. Read p. 295 until Example 5.
Example 5 • A juggler tosses a ball into the air. The ball leaves the juggler’s hand 4 feet above the ground and has an initial vertical velocity of 40 feet per second. The juggler catches the ball when it falls back to a height of 3 feet. How long is the ball in the air? Round the answer to the nearest thousandth.
h =– 16t2 + v0t + h0 • v0 = 40 feet per second • h0 = 4 feet • h = 3 feet
The is in the air about 2.525 seconds. Do Guided Practice #10. HW: p. 296 (4-48 mult of 4, 68)