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Quad Func Help

Stuck on some homework as the teacher was explaining it but not fully as there was about 10 minutes of the lesson left so it wasn't in depth teaching.
Just need some help or some steps on how to solve this question if anyone could help me:smile:
x^2-8x-29=(x+a)^2+b.
a) Find the value of A and the value of B
b) Hence, or otherwise, show that roots of-x^2-8x-29=0 are c+-droot5, where c and d are integers.
Original post by jshep000
Stuck on some homework as the teacher was explaining it but not fully as there was about 10 minutes of the lesson left so it wasn't in depth teaching.
Just need some help or some steps on how to solve this question if anyone could help me:smile:
x^2-8x-29=(x+a)^2+b.
a) Find the value of A and the value of B
b) Hence, or otherwise, show that roots of-x^2-8x-29=0 are c+-droot5, where c and d are integers.


Do you know what (xβˆ’4)2(x-4)^2 is
Reply 2
Original post by jshep000
Stuck on some homework as the teacher was explaining it but not fully as there was about 10 minutes of the lesson left so it wasn't in depth teaching.
Just need some help or some steps on how to solve this question if anyone could help me:smile:
x^2-8x-29=(x+a)^2+b.
a) Find the value of A and the value of B
b) Hence, or otherwise, show that roots of-x^2-8x-29=0 are c+-droot5, where c and d are integers.


a) x^2-8x-29=(x+a)^2+b.

use (x - 4)2

compare answer with (x+a)^2+b.


b) x^2-8x-29=0

use
If axΒ² + bx + c = 0 then x = .

compare answer with c+-d root 5

:smile:
Original post by Tutorsos

b) x^2-8x-29=0

use
If axΒ² + bx + c = 0 then x = .

compare answer with c+-d root 5

:smile:


The point of completing the square is to find a solution by re-arranging the answer found in (a)
Reply 4
I got x^2-8x-29=x^2+2ax+a^2+b

so 2ax must be -8. so a is -4? and -4^2 is 16. but i need -29. so b=-49?
for part B, i got x = 4±3√5
Original post by jshep000
I got x^2-8x-29=x^2+2ax+a^2+b

so 2ax must be -8. so a is -4? and -4^2 is 16. but i need -29. so b=-49?
for part B, i got x = 4±3√5


You seem to have an idea so

x2βˆ’8xβˆ’29=(xβˆ’4)2βˆ’16βˆ’29=(xβˆ’4)2βˆ’45x^2-8x-29 = (x-4)^2-16-29 = (x-4)^2 - 45

The next part is correct so I assume that you did mean 45 not 49
Reply 6
Original post by TenOfThem
You seem to have an idea so

x2βˆ’8xβˆ’29=(xβˆ’4)2βˆ’16βˆ’29=(xβˆ’4)2βˆ’45x^2-8x-29 = (x-4)^2-16-29 = (x-4)^2 - 45

The next part is correct so I assume that you did mean 45 not 49


Yeah my bad it was -45, thanks for the prompt none the less:biggrin:
Reply 7
Original post by jshep000
Stuck on some homework as the teacher was explaining it but not fully as there was about 10 minutes of the lesson left so it wasn't in depth teaching.
Just need some help or some steps on how to solve this question if anyone could help me:smile:
x^2-8x-29=(x+a)^2+b.
a) Find the value of A and the value of B
b) Hence, or otherwise, show that roots of-x^2-8x-29=0 are c+-droot5, where c and d are integers.

same bro.....

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