Question

Given the quadratic function f(x) = 25x2 – 100x + 100, find a value of x such that f(x) = 25.

Answer 1

no

Answer 2

what are you doing in class?

Answer 3

You know factorization of a quadratic expression?

Answer 4

maybe give me a min.

Answer 5

my answer is not making any sense

Answer 6

what are you doing in class?

the "AC" method, the quadratic formula, or completing the square?

Answer 7

x^2=-1

Answer 8

please answer my question then I can help you

Answer 9

quadratic formula

Answer 10

ok we have (-b +- sqrt(b^2-4ac))/2a right?

Answer 11

yep

Answer 12

what is a? what is b? and what is c?

Answer 13

25

Answer 14

x^2 -4x+3

Answer 15

this is the equation, ax^2+bx, + c

Answer 16

25x^2-100x+100 = 25

first we want to set it equal to 0 so we subtract 25 from both sides

25x^2-100x+75 = 0

then I would devide everything by 25 to make life nice.

x^2 -4x+3 = 0

Answer 17

so we are at x^2-4x+3 = 0

Answer 18

a=x^2, b=-4x , c=3

Answer 19

we just want the coefficients

Answer 20

a = 1, b = -4, c = 3

Answer 21

oh

Answer 22

now we have (-b+-sqrt(b^2-4ac))/2a = (-(-4)+-sqrt((-4)^2-4*1*3))/(2*1)
= (16+-sqrt(16-12))/2 = (16+-sqrt(4))/2 = (16+-2)/2

at this point we have two equations (16+2)/2 and (16-2)/2

so what is the final answer?

Answer 23

some correction: -(-4)=4,
(4+-sqrt(4))/2

Answer 24

it will be 2 correct answers

Answer 25

you all have lost me im gettin x=3,x=1

Answer 26

*now we have (-b+-sqrt(b^2-4ac))/2a = (-(-4)+-sqrt((-4)^2-4*1*3))/(2*1)
= (4+-sqrt(16-12))/2 = (4+-sqrt(4))/2 = (4+-2)/2

at this point we have two equations (4+2)/2 and (4-2)/2

we have 3 and 1

Answer 27

correct

Answer 28

yes ok

Answer 29

note there is a much nicer way of doing this

x^2-4x+3 = 0

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

x(x-1) -3(x-1) = 0

(x-1)(x-3) = 0

x-1 = 0 and x-3 = 0 so x = 1 and x = 3

Answer 30

TO check your answers you can plug 1 and 3 into original eq-n and will receive 25