1. SOLVING QUADRATIC INEQUALITIES RULE 1: If (x-a) (x-b) < 0 and a<b then a<x<b Rule 2: If (x-a)(x-b) >0 and a<b then x b

2. Exercise 3.3 Find the range of values for each of the following 1a) x 2 +5x-6 <0 Solution: The given inequality can be written as (x+6)(x-1)< 0 -6<x<1

3. 1f) (x+2)(x+3)  x+6 Solution: The given inequality can be written as x 2 +3x+2x+6  x+6 x 2 +4x  0 x(x+4)  0 Solutions are -4  x  0

4. 1g) (x-1)(5x +4) > 2(x-1) The given inequality can be written as 5x 2 +4x -5x -4 > 2x -2 5x 2 -3x -2 > 05x 2 2x (5x+2)(x-1) >0 x - 1 -5x 5(x+2/5)(x-1)>0 ___________ 5x 2 -2 -3x Solutions are x 1

5. 4. There is no real value of x for which mx 2 +8x +m =6. Find ‘m’ Since the equation has no real roots, the discriminant D < 0 Rewrite the given equation as follows mx 2 +8x +m-6 =0

6. a = m b = 8 c = m- 6 D = b 2 – 4ac = (8) 2 – 4 (m) m-6) = 64-4m 2 +24m = -4(m 2 -6m -16) < 0 ie m 2 -6m -16 >0 ie (m-8)(m+2) > 0 ie m 8

7. 13. The curve y= (k-6)x 2 -8x +k cuts x-axis at two points and has a minimum point. Find the range of values of ‘k’. Solution. (i)Since the curve has minimum value, k-6 > 0 i.e k>6---------(1) (ii) Since the curve cuts the x- axis at two points, its D>0 a = k-6 b = -8 c = k

8. D = b 2 – 4ac = (-8) 2 – 4 (k-6)(k) = 64-4k 2 +24k = -4(k 2 -6k -16)>0 ie k 2 -6k -16 <0 ie (k+2)(k-8) < 0 -2<k<8 -----------(2) Eqns (1) and (2)  6 < k <8