Question

Tell whether the equation x(x + 1) - x + y + 7 = 0 is an equation of linear equation in two variable or not.

A part of monthy expenses of a family on milk is fixed which is Rs. 500 and the remaining varies with the quantie of milk taken extra at the rate of Rs. 20 per litre, taking the quantity required as x litres and total expenditure on milk as Rs. y. Write a linear equation per day draw as a graph.

Answer 1

Hey there !

Solution:

Correction: It is -1 and not +1

Q1. Given Equation : x ( x - 1 ) - x + y + 7 = 0

Simplifying the equation we get,

=> x² - x - x + y + 7 = 0

=> x² -2x + y = -7

Since the highest degree of this equation is 2, it is a quadratic equation and not a linear equation.

Q2. So according to the question, Rs. 500 is a fixed cost. Also the remaining amount of extra milk taken is denoted as Rs. 20 per liter.

Total Expenditure = 500 + 20 ( x ) where x denotes the amount of milk bought in liters.

=> According to the new situation, Total Expenditure is 'y' and number of liters is x. So the equation would be:

500 + 20 ( x ) = y

=> 500 + 20x = y

=> 500 = y - 20x

Hence the linear equation is: $\boxed{ -20x + y = 500}$

Refer to the attachment for graph !

Hope it helped !