Question

the sum of a whole number and twice the square of the number is is 80. find the number?

Answer 1

Answer:

Number is 20 which has square as 40 and twice it is 80

Answer 2

Given - The sum of a whole number and twice the square of the number is 80.

Find - The whole number.

Solution - The equation as per mentioned details will be : X + 2x² = 80.

Taking all the variables to left side, equation will be : 2x² + X -80 = 0

Solving the formed quadratic equation by Shri Dharacharya formula -

-b +- ✓(b² - 4*a*c)/2*a.

Keeping the values in equation-

X = -1 +- ✓(1² -4*2*80)/2*2

X = (-1 +- ✓641)/4

Since x is an whole number, ignoring the negative answer.

X = 24.3/4

X = 6.08.

Rounding the resultant value of X to nearest whole number, X = 6.

Hence, the nearest whole number is 6.