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if alpha and beta are the roots of the equation 3x^2-9x+2=0 find the values of: (I) alpha ×beta + alpha^2 × beta. (ii) alpha^2-alpha×beta+beta^2​

User Jianhong
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1 Answer

4 votes

Answer:

in steps

Explanation:

The question did not state if alpha>beta or alpha<beta, so the answer will have 2 answers for each questions

3x²-9x+2=0

x = (-(-9) ± √(-9)²-4*(3)*(2)) / (2*3)

x = (9 + √57) / 6 or x = (9 - √57) / 6 (alpha and beta) or (beta and alpha)

(I) alpha (a) ×beta (b) + alpha² × beta = ab (1+a)

= ((9 + √57) / 6) ((9 - √57) / 6) (1 + (9 ± √57))

= ((9² - (√57)²)/36) (10 ± √57)

= (24/36) (10 ± √57)

= 2/3 (10 ± √57) or (11.7 or 1.63)

(ii) alpha²-alpha×beta+beta² = a² -2ab + b² +ab = (a - b)² + ab

if a is alpha

=​ ((9 + √57) / 6) - ((9 - √57) / 6)) + ((9 + √57) / 6) ((9 - √57) / 6))

= √57/3 + 2/3

= (√57 + 2) / 3

if a is beta

((9 - √57) / 6) - ((9 + √57) / 6)) + ((9 - √57) / 6) ((9 + √57) / 6))

= - √57/3 + 2/3

= - (√57 + 2) / 3

User Kerim Emurla
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