Question

5. Simplify the expression and find its value when p= 4 and q = -5:

(i) 3 ( p2q + pq2 – pq ) – 6 pq + 3pq2

Answer 1

-180

Explanation:

3 ( p2q + Pq2 - pq ) - 6 pq +3pq2

3 [(4)(2)(-5) + (4)(-5)(2) - (4)(-5)] -6 (4)(-5) +3(4)(-5)(2)

3(-40-40+20) + 120 -120

3(-60) +0

-180+0

-180

Answer 2

• Answer: -180

Explanation:

`\bf \blue{ \boxed{ \bf p = 4 \: \: and \: \: q = - 5 \Rightarrow pq = 4 * ( - 5) = - 20}}`

3(p2q + pq2 - pq) - 6pq + 3pq2 =

3[-20 × 2 + (-20) × 2 - (-20)] - 6 × (-20) + 3 × 2 × (-20) =

3[-40 + (-40) + 20] - 6 × (-20) + 3 × 2 × (-20) =

3(-40 - 40 + 20) - 6 × (-20) + 3 × 2 × (-20) =

3(-80 + 20) - 6 × (-20) + 3 × 2 × (-20) =

3 × (-60) - 6 × (-20) + 3 × 2 × (-20) =

-180 + 120 + 6 × (-20) =

-180 + 120 + (-120) =

-180 + 120 - 120 =

-60 - 120 = -180