Five times a number is added to two times it’s square. if the result is 168, find the number.

let number be x.

by the question

5x+2(x^2)=168

2x^2+5x-168=0

2x^2 +(21-16)x-168=0

2x^2+21x-16x-168=0

2x^2-16x+21x-168=0

2x(x-8)+21(x-8)=0

(x-8)(2x+21)=0

either

x-8=0

so. x=8

or

2x+21=0

2x=-21

x=-21/2

therefore x=8 or x=-21/2

ANSWER:

Five times a number is added to two times it’s square. The value of “x” is either 8 or -10.5

SOLUTION:

Let the number be “x”

Given, Five times a number is added to two times it’s square.

Five times a number + two times it’s square .Hence we get

5x + 2x square

Also given that, result is 168. So the above equation is equal to 168

Let us find roots of above equation using quadratic formula.

Here, a = 2, b = 5, c = -168

Substitute the values in formula we get

On simplification we get,

x = 8, -10.5

Hence, the value of x is either 8 or -10.5

5   1/4   miles per hour

step-by-step explanation:

15   3/4 / 3 = 5   1/4