Question

7. If p = 3, q = -5, and r = 4, find the value of : (i) p2 - 2qr (ii) q2 - 3pr (iv) pq + qr + rp (v) 3pq + 10pr + 2qr (iii) r2 - pq (vi) p² + q2 + r2 - pq - qr - pr
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Answer 1

Answer:

(i) 49 , (ii) -11 , (iii) 31 , (iv) -23 , (v) 35 , (vi) 73

Step-by-step explanation:

(i) p2 - 2qr

   3^2 - 2*[-5*4]

 = 9+40

 = 49

(ii) q2 - 3pr

    [-5]^2 - 3*3*4

  = 25 - 36

  = -11

(iii) r2 - pq

    4^2 - 3*-5

  = 16+15

  = 31

(iv) pq + qr + rp

     3*-5 + -5*4 + 4*3

  = -15-20+12

  = -23

(v) 3pq + 10pr + 2qr

    3*3*-5 + 10*3*4 + 2*-5*4

  = -45 + 120 - 40

  = 35

(vi) p² + q2 + r2 - pq - qr - pr

    3² + [-5]² + 4² -3*[-5] -[-5]4 - 3*4

  = 9+25+16+15+20-12

  = 73

Answer 2

Answer:

7. if p= 3 , q = - 5 and r = 4 , find the value of : iii) r2 - pq =

Step-by-step explanation:

r2 - pq =

4 * 6 - 3 * 5

= 16 + 15

= 31

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