Question

x^2+2x-400 use factorisation method ​

Answer 1

Given,

The quadratic equation is x^+2x-400.

Now to solve a quadratic equation we can use 3 methods =>

1)Completing Square Method,

2)Middle term Split method, and

3)By Quadratic formula.

Here we will be using the quadratic formula method to solve the quadratic equation as it is not suitable here to solve the equation by factorization method --->

d=b^2 - 4×a ×c

=>d = (2)^2 -{4 × 1×(-400)}

=>d = 4 + 1600

=>d = 1604.

Hence we have =>

x = $\dfrac{-b\pm\sqrt d}{2\times{a}}$

=>x=$\dfrac{-2\pm\sqrt1604}{2\times1}$

=>x = $\dfrac{-2\pm\sqrt1604}{2}$

So,

either,

x= $\dfrac{-2+\sqrt1604}{2}$

or

x = $\dfrac{-2-\sqrt1604}{2}$

REMEMBER

1)Here

d = discriminant (decides the nature of roots or zeroes of a quadratic equation.

a)when d = 0

then the quadratic equation will have the same real and equal roots.

b)when d>0

then the quadratic equation will have two real and distinct roots.

c)when d<0

then the quadratic equation will have no real roots i.e it will have imaginary roots.

Remember these 3 methods are to be used to solve the quadratic equation according to the question given.