IMPORTANT TIPS:
- ax+b = 0 (a,b are real numbers and a is nonzero) is a linear equation of one variable. Thus, 2x+3 = 0 and 0.4x-5 = 0 are linear equations of one variable.
- ax+by+c = 0(a,b,c are real numbers and a and b are not equal to zero simultaneously)is a linear equation of two variables. Thus, 3x-2y+4 = 0 and(2x/3)+(4y/5)-6 = 0 are linear equations of two variables.
- y = (-a/b)x-(c/b) or y = (-ax-c)/b is called y-form of the equation ax+by+c = 0
- If we have only one equation, ax+by+c = 0, then it has got infinite solutions because for each value of x we get some value of y which satisfies the equation.
- If we have a pair of equations a1x+b1y+c1 = 0 and a2x+b2y+c2 = 0,then there are three possibilities:
- The equations have a particular(unique) solution where unique values of x and y satisfy both equations. This happens when a1b2-a2b1≠ 0
- The equations do not have a solution, i.e. there is no set of values of both x and y which can satisfy both equations. This happens when a1b2-a2b1 = 0 and either b1c2-b2c1≠ 0 or c1a2-c2a1≠ 0
- The pair of equations has infinite solutions.This happens when a1b2-a2b1 = b1c2-b2c1 = c1a2-c2a1 = 0
- METHOD OF CROSS MULTIPLICATION:
Let the given pair of equations be:a1x+b1y+c1 = 0 a2x+b2y+c2 = 0 (a1, b1 and a2, b2 are not zero simultaneously)
To understand the procedure READ THE DETAILS IN THE FOLLOWING IMAGE and
To read the details clearly ENLARGE IT by opening it in another window.
What we have done while going from step (A) to step (B) is :
Write the product of b1 andc2 (downward arrow) minus the product of b2 and c1 (upward arrow) below x. Follow the same procedure for y and 1.
So, we get (B). NEXT ?x = b1c2 - b2c1
a1b2 - a2b1
and
y = c1a2 - c2a1
a1b2 - a2b1
Thus, we get the values of x and y which satisfy the given pair of equations. - PRACTICAL PROBLEMS:
In solving practical problems, one must not forget that it is the lack of proper understanding of the language that makes the solution difficult.So, while solving practical problems with the help of linear equations :- Read the statement carefully.
- Analyse it thoroughly.
- Form correct equations.
This requires great patience and exhaustive practice.More you practise, more you understand the method.
DESSERT
2 is the only prime which is even!