2題(20點)數學唔該><急急

[匿名]

2012-10-12 4:39 am

find the values of the constants P,Q and R in each of the following identities.

4.(2c-1)^2-P≡Qx^2+Rx+5
5.(x-P)^2+6≡x(Qx+2)-R

回答 (2)

胡雪8°

2012-10-12 8:58 am

✔ 最佳答案

4.
The question should be： (2x - 1)² - P ≡ Qx² + Rx + 5

(2x - 1)² - P ≡ Qx² + Rx + 5
4x² - 4x + 1 - P ≡ Qx² + Rx + 5
4x² - 4x + (1 - P) ≡ Qx² + Rx + 5

Compare the constant terms on the both sides :
1 - P = 5
P = -4

Compare the x² terms on the both sides :
Q = 4

Compare the x terms on the both sides :
R = -4

=====
5.
(x - P)² + 6 ≡ x(Qx + 2) - R
x² - 2Px + P² + 6 = Qx² + 2x - R
x² - 2Px + (P² + 6) = Qx² + 2x - R

Compare the x terms on the both sides :
-2P = 2
P = -1

Compare the x² terms on the both sides :
Q = 1

Compare the constant terms on the both sides :
-R = P² + 6
-R = (-1)² + 6
R = -7

參考: 胡雪

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2012-10-12 4:52 am

4.) 2c-1)^2-P≡Qx^2+Rx+5

(4c^2-2C+1)-P≡Qx^2+Rx+5

4c^2-2C+1-P≡Qx^2+Rx+5

5.(x-P)^2+6≡x(Qx+2)-R

x^2-2Px+P^2+6≡Qx+2-R

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