Question

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If (p +9+r = 5) and pq + qr + rp = 10 then the value of p3 +93 +p3 – 3pqr will be
a 15
b -15
c 25
d-25
​

Answer 1

Answer:

Given:-)

→ p + q + r = 6.

→ pq + qr + rp = 5.

To Find :-)

→ p³ + q³ + r³ - 3pqr.

▶ We have,

=> p + q + r = 6.

[ Squaring both side ]

=> ( p + q + r ) ² = 6².

=> p² + q² + r² + 2 ( pq + qr + rp ) = 36.

=> p² + q² + r² + 2 ( 5 ) = 36.

=> p² + q² + r² + 10 = 36.

=> p² + q² + r² = 36 - 10.

=> p² + q² + r² = 26.

▶Now,

=> p³ + q³ + r³ - 3pqr = ( p + q + r ) ( p² + q² + r² - ( pq + qr + rp ) ).

= ( 6 ) ( 26 - (5) ).

= 6 × 21.

= 126.

✔✔Hence, it is solved ✅✅.

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Step-by-step explanation:

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Answer 2

Step-by-step explanation:

If (p +9+r = 5) and pq + qr + rp = 10

formula of p³+9³+r-3pqr=(p+q+r)(p²+q²+r ²-pq-qr-pr)

after squaring both side =36

p²+q²+r²=36-10=26

now 6×(26-5)

=6×21

=126

hope it will help you friend