For a polynomial of the form ax^2+bx+c rewrite the middle term as a sum of two terms whose product is a*c=2*(−49)=−98 and whose sum is b=7.
2x^2+(−7+14)x−49
= 2x^2+(−7x+14x)−49
= 2x^2−7x+14x−49
Group the first two terms and the last two terms.
= (2x^2−7x)+(14x−49)
Factor out the greatest common factor (GCF) from each group.
= x(2x−7)+7(2x−7)
Factor the polynomial by factoring out the greatest common factor, 2x−7.
= (2x−7)(x+7)
Hope this helps !