Factorise : 84 - 2r - 2r²
Solution:
Given, the polynomial is 84 - 2r - 2r².
We have to factorise the polynomial.
On factoring by splitting the middle term,
-2r² - 2r + 84
-2(r² + r - 42)
-2(r² + 7r - 6r - 42)
-2(r(r + 7) - 6(r + 7))
-2((r - 6)(r + 7))
2((6 - r)(r + 7))
Therefore, the factors are 2(6 - r) and 2(r + 7).
✦ Try This: Factorise : 9x² - 3x - 2
Given, the polynomial is 9x² - 3x - 2.
We have to factorise the polynomial.
On factoring by splitting the middle term,
9x² - 3x - 2
9x² + 4x + 2x + 8
x(x + 4) + 2(x + 4)
(x + 4)(x + 2)
Therefore, the factors are (x + 4) and (x + 2).
☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 2
NCERT Exemplar Class 9 Maths Exercise 2.3 Problem 23(iv)
Factorise : 84 - 2r - 2r²
Summary:
Terms that have different variables and different powers are known as unlike terms. On factoring 84 - 2r - 2r² the factors are 2(6 - r) and 2(r + 7)
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