Quadratic word problems, and choosing a method
Grade 9 Math Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
Kira tosses a basketball straight up at 40 feet per second. Its height in feet is h = -16t² + 40t. It lands when h = 0. When does it land, in seconds?
Luz launches a toy foam rocket straight up at 56 feet per second. Its height in feet is h = -16t² + 56t. It lands when h = 0. When does it land, in seconds?
Milo's garden bed is x meters wide. Solving x² + 3x - 40 = 0 gives x = 5 or x = -8. Which answer fits the story?
- Neither one fits
- x = 5, because a width must be positive
- x = -8
- Both x = 5 and x = -8, since both come from the equation
Noah's rug is x feet long. Solving x² + 2x - 63 = 0 gives x = 7 or x = -9. Which answer fits the story?
- x = 7, because a length must be positive
- x = -9
- Both x = 7 and x = -9, because both answers work in the equation
- Neither one fits
Pia throws a ball from a balcony. It lands when 16t² - 32t - 20 = 0, so t = 2.5 or t = -0.5. Which answer fits the story?
- t = -0.5
- Both t = 2.5 and t = -0.5, since both come from the equation
- t = 2.5, because a time must be positive
- Neither one fits
Ren's square quilt patch is x inches on a side. Solving x² - x - 30 = 0 gives x = 6 or x = -5. Which answer fits the story?
- x = 6, because a side must be positive
- x = -5
- Both x = 6 and x = -5
- Neither one fits
Tala wants to solve one of these by square roots, with no factoring. Which can be solved by taking square roots?
- x² + 4x = 12
- 3x² - 12 = 0
- x² - 5x + 6 = 0
Zee will solve one of these by square roots, with no factoring. Which can be solved by taking square roots?
- x² - 2x = 25
- (x - 2)² = 25
- x(x - 2) = 25
Ari's robot can only take square roots. Its list has three equations. Which can be solved by taking square roots?
- 5x² = 80
- 5x² + x = 80
- x² + 5x - 80 = 0
Bo's math book asks for square roots only, no factoring. Which can be solved by taking square roots?
- x² + 9 = 45
- x² + 9x = 45
- x² + 9x + 45 = 0