3psilon
SAT help ? In the equation, K and m are constants . If the equation is true for all values of x, what is the value of m?



This Question is Closed

3psilon
Best Response
You've already chosen the best response.
0
\[(x8)(xk) = x^{2} 5kx + m\]

bahrom7893
Best Response
You've already chosen the best response.
0
simplify the left side:
x^2  kx  8x + 8k = x^2  (k+8)x + 8k

bahrom7893
Best Response
You've already chosen the best response.
0
x^2  (k+8)x + 8k = x^2  5kx + m

bahrom7893
Best Response
You've already chosen the best response.
0
thus you know that k+8 = 5k

bahrom7893
Best Response
You've already chosen the best response.
0
and 8k = m

robinfr93
Best Response
You've already chosen the best response.
0
just what bahrom said

bahrom7893
Best Response
You've already chosen the best response.
0
Now just solve for both.

robinfr93
Best Response
You've already chosen the best response.
0
bahrom mate can ya help me out with a sum of my own??

robinfr93
Best Response
You've already chosen the best response.
0
@bahrom7893

bahrom7893
Best Response
You've already chosen the best response.
0
@robinfr93 let me see the question

3psilon
Best Response
You've already chosen the best response.
0
@bahrom7893 What does it mean by true for all values of x?

3psilon
Best Response
You've already chosen the best response.
0
I don't see how you got k+8 = 5k Where did everything else go?

bahrom7893
Best Response
You've already chosen the best response.
0
it just means equate the two equations.

bahrom7893
Best Response
You've already chosen the best response.
0
I'm equating the coefficients:
x^2  (k+8)x + 8k = x^2  5kx + m

bahrom7893
Best Response
You've already chosen the best response.
0
dw:1347995814720:dw

bahrom7893
Best Response
You've already chosen the best response.
0
dw:1347995848017:dw

bahrom7893
Best Response
You've already chosen the best response.
0
for those two equations to be equal to each other for all x, k+8 has to equal 5k and 8k must equal m

3psilon
Best Response
You've already chosen the best response.
0
Could it go the other way around? Like (k+8) = m? @bahrom7893

bahrom7893
Best Response
You've already chosen the best response.
0
No it couldn't, since x coefficients have to equal to corresponding x coefficients

bahrom7893
Best Response
You've already chosen the best response.
0
k+8 is coefficient of x^1, and so is 5k
both 8k and m are coefficients of x^0

3psilon
Best Response
You've already chosen the best response.
0
Ohhhh I see now ok ok thanks