Question 177209
8)  Factor x^2 + 6x - 40
   Ans:
     Given equation is x^2+6x-40.
     (To find the factor for this type of equation first we see that there is any coefficient in the high factor)   
     Here no coefficient with high power.
     So first we consider the constant i.e.,-40.
     Next we split this constant into mutliple of two variables also we note that the addition of two variables gives the coefficient of second higher power.   
      Therefore, -40 = 10 x -4   (10-4=+6)
      
      Now the given equation can be written as 
       x^2+10x-4x-40 = 0
       x(x+10)-4(x+10)=0
       (x+10)(x-4)=0
        x=-10 and x=4
      
      Thus the factor x=-10,4.
       


 
 

9)  Factor  3x^2 + 2x – 5
    Ans:
    Given equation is 3x^2+2x-5=0.
    Here there is coefficient with high power (x^2).
    So that coefficient is mutliply with the constant.
    i.e.,  3x(-5)= -15
           -15 = 5 x-3 = 2(second high power coefficient)
    Now the given equation can be written as
     3x^2-3x+5x-5=0
     3x(x-1) +5(x-1)=0
     (3x+5)(x-1)=0
     3x+5=0 and x-1=0
     3x=-5 and x=1
     x=-5/3 and x=1

     Thus the factor of the given equation is
     x = -5/3, 1