Question

The sum of a whole number and twice the square of the number is 10. Find the number.

Answer 1

Hey there !

Solution:

Let the number be x

=> x + 2x² = 10

=> 2x² + x - 10 = 0

Factorising the quadratic equation we get,

=> 2x² + 5x - 4x - 10 = 0

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

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

=> x = 2, -5/2

Since x is a whole number, -5 / 2 wont be applicable.

Hence x = 2.

Hence the number is 2.

Hope my answer helped !

Answer 2

heya...

Here is your answer...

Let us take the number as x.

x + 2x^2 = 10

x+2x^2-10 = 0

2x^2+5x-4x-10 =0

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

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

x = 2 or -5/2.

Here -5/2 is not a whole number. so the value of x is 2.

It may help you...☺☺