Question

factorise(1) 8x^2+14x+3 (2)18x^2+9x-5 (3)x^2-11x-33​

Answer 1

hi there!!!

1. 8x^2+14x+3=0

8x^2+12x+2x+3=0

8x^2+2x+12x+3=0

2x(4x+1) +3(4x+1) =0

(4x+1) (2x+3) =0..... factors

hence,

x= -1/4 or x= -3/2

2. 18x^2+9x-5=0

18^2+15-6x-5=0

18x^2-6x+15x-5=0

6x(3x-1)+5(3x-1)=0

(3x-1) (6x+5) =0....... factors

hence,

x= 1/3 or x= -5/6

3.x^2-11x-33=0

comparing with ax^2+bx+c= 0,

we get,

a=1, b= -11 and c= -33

by formula method,

b^2-4ac= (-11) ^2-4×1×(-33)

= 121+4×33

= 121+ 132

= 253

therefore,

substituting in the formula,

= -b+-√b^2-4ac

2a

= 11+-√253

2

therefore,

x= 11+√253/2 or x= 11-√253/2

hope this helps!!! ☺✌❤

Answer 2

Answer:

Step-by-step explanation:

1. 8x^2+14x+3=0

8x^2+12x+2x+3=0

8x^2+2x+12x+3=0

2x(4x+1) +3(4x+1) =0

(4x+1) (2x+3) =0..... factors

hence,

x= -1/4 or x= -3/2

2. 18x^2+9x-5=0

18^2+15-6x-5=0

18x^2-6x+15x-5=0

6x(3x-1)+5(3x-1)=0

(3x-1) (6x+5) =0....... factors

hence,

x= 1/3 or x= -5/6

3.x^2-11x-33=0

comparing with ax^2+bx+c= 0,

we get,

a=1, b= -11 and c= -33

by formula method,

b^2-4ac= (-11) ^2-4×1×(-33)

= 121+4×33

= 121+ 132

= 253

therefore,

substituting in the formula,

= -b+-√b^2-4ac

2a

= 11+-√253

2

therefore,

x= 11+√253/2 or x= 11-√253/2