# C1 helpWatch

#1
Hey everyone. Just a few questions.

1 It is given that f(x) = (x - 2)^2 - p(x + 1)

a. Find the values of p for which the equation f(x) = 0 has 2 equal roots

b. Show that, when p = 4, f(x) has a minimum value of -16

c. Given that the curver y = f(x) has a turning point when x = 3, find the value of p

2. Complete the square of y = 10 - 6x - x^2

Sorry i know these sound really easy but i'm stumped.

Thankyou
0
9 years ago
#2
Which parts are you stuck on? How much of it can you do?
0
9 years ago
#3
(Original post by Umairy363)
Hey everyone. Just a few questions.

1 It is given that f(x) = (x - 2)^2 - p(x + 1)

a. Find the values of p for which the equation f(x) = 0 has 2 equal roots

b. Show that, when p = 4, f(x) has a minimum value of -16

c. Given that the curver y = f(x) has a turning point when x = 3, find the value of p

2. Complete the square of y = 10 - 6x - x^2

Sorry i know these sound really easy but i'm stumped.

Thankyou
Starting with a) represent f(x) in quadratic from () then equate values of p for which the discriminant >0.
0
9 years ago
#4
(Original post by Umairy363)
Hey everyone. Just a few questions.

1 It is given that f(x) = (x - 2)^2 - p(x + 1)

a. Find the values of p for which the equation f(x) = 0 has 2 equal roots

b. Show that, when p = 4, f(x) has a minimum value of -16

c. Given that the curver y = f(x) has a turning point when x = 3, find the value of p

2. Complete the square of y = 10 - 6x - x^2

Sorry i know these sound really easy but i'm stumped.

Thankyou
Small has done 1 and I cant do any better but here is 2.

to complete the square you need it in the form

So just multiply out the brackets and compare coefficients. For example you would have

Do the same for the x's and the constants and your onto a winner.
0
9 years ago
#5
(Original post by Umairy363)
Hey everyone. Just a few questions.

1 It is given that f(x) = (x - 2)^2 - p(x + 1)

a. Find the values of p for which the equation f(x) = 0 has 2 equal roots

b. Show that, when p = 4, f(x) has a minimum value of -16

c. Given that the curver y = f(x) has a turning point when x = 3, find the value of p

2. Complete the square of y = 10 - 6x - x^2

Sorry i know these sound really easy but i'm stumped.

Thankyou
b) complete the square so find the minimum value.

c) again complete the square and use the value of p to determine turning point.
0
#6
(Original post by Small123)
b) complete the square so find the minimum value.

c) again complete the square and use the value of p to determine turning point.
I managed to get 'b' but not 'c'. I don't have p, i hae x, but i've tried putting it in f(x) and i'm getting 17/4, the actual answer is 2 ??
0
9 years ago
#7
(Original post by Umairy363)
I managed to get 'b' but not 'c'. I don't have p, i hae x, but i've tried putting it in f(x) and i'm getting 17/4, the actual answer is 2 ??
Are you allowed to use calculus?
0
#8
(Original post by Small123)
Are you allowed to use calculus?
I would have used calculus, if i was allowed, i'm a review exercise from the beginning of the book, and they havent taught us calculus yet, in the book so i'm assuming no.
0
9 years ago
#9
(Original post by Umairy363)
I would have used calculus, if i was allowed, i'm a review exercise from the beginning of the book, and they havent taught us calculus yet, in the book so i'm assuming no.
Interesting. Ill give it a try and report back
0
9 years ago
#10
(Original post by Umairy363)
I would have used calculus, if i was allowed, i'm a review exercise from the beginning of the book, and they havent taught us calculus yet, in the book so i'm assuming no.
Alright could you post your working because I get 2.
0
#11
(Original post by Small123)
Alright could you post your working because I get 2.

f(x) = x^2 + 4 - 4x - p(x+1)
-16 = 9+4 - 12 - px - p
-17 = -3p-p
-17 = -4p
p = 17/4
0
9 years ago
#12
(Original post by Umairy363)
f(x) = x^2 + 4 - 4x - p(x+1)
-16 = 9+4 - 12 - px - p
-17 = -3p-p
-17 = -4p
p = 17/4
Rearranging f(x) to give you . Then complete the square and find the value of p which yields a min at x=3.
0
#13
(Original post by Small123)
Rearranging f(x) to give you . Then complete the square and find the value of p which yields a min at x=3.
oh. Ok i see, thankyou very much.
0
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