the product of zeroes of P(x) = ax3 -6x2
+11x - 6 is 4 , then a =
Answers
roots of given polynomial is in AP
let P- r , P, and P+ r are the roots of
f( x) = ax³ + 3bx² + 3cx + d
sum of roots = -coefficient of x²/coefficient of x³
P -r + P + P+ r = -( 3b/a)
3P = -( 3b/a)
P = -b/a -----------(1)
sum of products of two roots =
( P -r)×P + P×(P+r) + (P-r)(P+r) = coefficient of x/coefficient of x³
P² -Pr + P² +Pr + P² -r² = 3c/a
3P² - r² = 3c/a ------------------(2)
again ,
products of all roots = -constant /co-efficient of x³
(P-r)×P× (P+r) = - d/a
P³ - Pr² = -d/a ----------(3)
now,
equation (1) put in eqn (2) ,
3(-b/a)² -r ² = (3c/a)
r² = 3(b²/a²) -3(c/a) ----------(4)
eqn (4) and (1) put in eqn(3)
(-b/a)³ -(-b/a)( 3b²/a² -3c/a ) = -d/a
-b³/a³ +b/a(3b²/a² -3c/a ) = -d/a
-b³/a³ +3b³/a³ -3bc/a² = - d/a
2b³/a³ -3bc/a² = -d/a
2b³ -3abc = -da²
2b³ -3abc + a²d = 0
hence, proved ///
Answer:
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