3x^2+x-4=0

Question

Solve for x 

                                                                                                

Answer 1

3x^2+x-4=0

 the numbers are very small

3 is prime and 4 is 2*2 or 1*4

 

(3x   )(x   ) so far

(3x   4)(x  1) so far

+x is positive, so...

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

3x+4=0

3x=-4

x=-4/3

x-1=0

x=1

  

Answer 2

Hi Ela,

 

3x² +x-4=0    

Using factorisation ,

3x² +4x-3x-4= 0

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

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

 x-1 = 0 or 3x+4= 0

  x= 1 or x=-4/3

 Check your answer.

Answer 3

3x² + x - 4 = 0

 

Use the quadratic formula.

 

a = 3

b = 1

c = -4

 

x = (1/ 2a) [-b ± √(b² - 4ac)]

 

x = (1 / 2*3) [-1 ± √[1² - 4(3)(-4)] = (1/6)(-1 ± √49)

 

x = (1/6)(-1 ± 7)

 

x = -4/3 or 1

 

You can substitute these values back into the equation to test the solution.