Exercise 12.3
1. Carry out the following divisions.
(ii)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
(iv)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
(v)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
2. Divide the given polynomial by the given monomial.
(ii)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
(iv)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
(v)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
3. Work out the following divisions.
(v) 96abc(3a – 12)(5b – 30) ÷ 144(a – 4)(b – 6)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
4. Divide as directed.
(iii) 52pqr(p + q)(q + r)(r + p) ÷ 104pq(q + r)(r + p)
- Do the division and cancel out the common factors
- We get:
- Let's try it out
- And we have found the answer
5. Factorise the expressions and divide them as directed.
(iii)
- Factorised form of numerator:
- Now let's check our answer, taking out the common factor of 5, we get:
5 p 2 − 5 p + 4 - This can be re-written as:
5 p 2 − 5 p + 4 = 5 p 2 − p − 4 p + 4 = 5 p − 1 p − 4 - Now,
5 p 2 − 25 p + 20 ÷ =p − 1 - Thus, the quotient is
5 × after cancelling the common factor: (p-1)p − 4
(iv)
- Factorised form of numerator:
- On factorising
, we get:z 2 + 6 z − 16 z + 8 z − 2 - This gives us:
4 yz z 2 + 6 z − 16 = 4 yz z − 2 z + 8 - Now,
4 yz z 2 + 6 z − 16 ÷ 2 y =z + 8 - Thus, the quotient is
2 z after cancelling the common factors:z − 2 y andz + 8
(vi)
- Factorised form of numerator:
- Using the identity-
a 2 − b 2 = a + b , we get:a − b 3 x + 4 y 3 x − 4 y - This gives us:
12 xy 9 x 2 − 16 y 2 = 12 xy 3 x + 4 y 3 x − 4 y - Now,
12 xy 9 x 2 − 16 y 2 ÷ 4 xy =3 x + 4 y - Thus, the quotient is
3 after cancelling the common factors:3 x − 4 y x ,y and3 x + 4 y
(vii)
- Factorised form of numerator:
- Now let's check our answer, taking out the common factors of 2, 39 and
, we get:y 3 5 y − 7 5 y + 7 - This gives us:
39 y 3 50 y 2 − 98 = 78 × y 3 × 5 y + 7 5 y − 7 - Now,
39 y 3 50 y 2 − 98 ÷ 26 y 2 =5 y + 7 - Thus, the quotient is
3 y after cancelling the common factors: 26,5 y − 7 andy 2 5 y + 7