Question

The product of two consecutive integers is 420. Which quadratic equation can be used to find x, the lesser number? x2 + 1 = 420 x2 + 2 = 420 x2 + x = 420 x2 + 2x = 420v

Answer 1

Answer:

The answer is x^2 + x =420

Step-by-step explanation:

It is given that

The product of two consecutive integers is 420

Le x be the first number, then

second number is the next consecutive number of x which is (x +1)

The product of these numbers can be written as

x (x + 1) which is equal to 420

x (x + 1)  = 420

x^2 + x = 420

So the quadratic equation is

x^2 + x = 420

Answer 2

Let take the integer as ‘’a’’ and its consecutive is ‘’a + 1’’

Formula: a * (a + 1) = a + a2

a * (a + 1) = a + a2 =  420

a2 + a - 420 = 0 --- > equation 1

Step 1: Factoring the equation1, we get the integer.

a2 + a - 420 = 0

a2 -20a + 21a - 420 = 0

a (a - 20) + 21 (a - 20) = 0

(a -20) (a + 21) = 0

Possibilities of ‘’a’’ value is

a = 20

a = -21