Quick Check: STAAR DAY 13 A.8a

Solve by factoring: x² - 9x + 20 = 0

• x = -4 and x = -5
• x = 20 and x = -9
• x = 4 and x = 5
• x = -4 and x = 5

Solve by using the quadratic formula.

7x² - 26x - 8 = 0

• x = -1 and x = -7/8

• x = 4 and x = -2/7

• x = -4 and x = 2/7

• x = 4 and x = -7/2

Solve for x. Round to the nearest hundredth if necessary.

3x² = 16x + 12

• x = -0.67 and x = 6

• x = -6 and x = 0.67

• x = 3.33 and x = 18

• x = -3.33 and x = 18

7x² - 26x - 8 = 0

• x = -1 and x = -7/8
• x = 4 and x = -2/7
• x = -4 and x = 2/7
• x = 4 and x = -7/2

What should you do first in solving this equation?
x² + 6x - 13 = 3

• Get factored form
• Write down: a=1, b=6, c=-13
• Make it equal 0 by subtracting 3 on each side
• Type it all in a calculator.

What is this formula?

• This is the speed of light formula.
• This is the quadratic formula.
• This is the zero product property.
• This is scary.

Solve using the quadratic formula.
2x² - 9x - 35 = 0

• x = 7/2, x = -6
• x = -5/2, x =5
• x = -3/7, x =6
• x = -5/2, x = 7

Heather dropped a water balloon over the side of her school building from a height of 80 feet. The approximate height of the balloon at any point during its fall can be represented by the following quadratic equation:

h = -16t² + 80

About how long did it take for the balloon to hit the ground?

• 1.73 seconds

• 2.24 seconds

• 2.45 seconds

• 2.83 seconds

Rafael drops a ball from a third-story window. This equation represents the approximate height, h, in meters, of the ball above the ground after it falls for t seconds.

h = -5t² + 45

When is the ball at ground level?

• only at t = 0 seconds

• only at t = 3 seconds

• only at t = 9 seconds

• at both t = 0 seconds and t = 3 seconds