Question

The quadratic equation 2x^2+4x-30=0 has two solutions. one of the solutions is x=3 the other solution is?

Answer 1

Explanation:

`2x^2+4x-30=0\\<=> x^2+2x-15=0`

so we know that the sum of the two solutions is -2 and the multiplication -15

so we are looking for x so that

x+3=-2 and 3x=-15

it gives x = -5

another way to do it is to put (x-3) in factor as we know that 3 is one of the solutions it gives

`2x^2+4x-30 = 2(x-3)(x+5)`

and then the second solution is -5

Answer 2

2x^2+4x-30=0

Explanation:

2x^2+10x-6x-30=0

2x(x+5)-6(x+5)=0

(2x-6)(x+5)=0

2x-6=0 x+5=0

x=6/2 x=-5

x=3