Question

The height of a soccer ball kicked in the air is given by the quadratic equation
h(t)=-4.9(t-2.1)^2+23, where time, t, is in seconds and height, h(t), is in metres

Is the ball still in the air after 6 seconds?

Answer 1

if you solve h(t) = 0 you'll find how long the ball is in the air

Answer 2

what values of t will make h(t) = 0?

Answer 3

h(t)=-4.9(t-2.1)^2+23 = 0
(t - 2.1)^2 = -23/-4.9

can you finish this?

Answer 4

(t - 2.1)^2 = 4.694
t - 2.1 = sqrt 4.694

Answer 5

h(t)=-4.9(t-2.1)^2+23 = 0
(t - 2.1)^2 = -23/-4.9
(t+4.41)=4.69

@welshfella i don't know what to do next

Answer 6

t - 4.41 is incorrect
the square root of (t - 2.1)^2 is simply (t - 2.1)

Answer 7

(t - 2.1)^2 means 'all of t - 2.1 is sqaured so the square root of this is simply t - 2.1

Answer 8

ok?

Answer 9

so t - 2.1 = sqrt 4.69
t = 2.17 + 2.1 = 4.27 seconds

so the ball is not in the air after 6 seconds

Answer 10

total time in the air = 4.27 seconds

Answer 11

OK? any questions?

Answer 12

@welshfella oh okay I see, thank you!

Answer 13

yw