maths questions for class ix
Answers
Solution :
Question 1 :-
Given equation : 2x + πy = 4
If y = 0 , then
=> 2x + πy = 4
=> 2x + π•0 = 4
=> 2x = 4
=> x = 4/2
=> x = 2
Hence ,
(2,0) is a solution of the given equation .
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Question 2 :-
Given equation : 3bx - y = 9
It is said that , (3,3) is one of the solution of the given equation .
Thus ,
The coordinates of the point (3,3) must satisfy the given equation .
Now ,
Putting x = 3 , y = 3 in the given equation ,
We have ;
=> 3bx - y = 9
=> 3b•3 - 3 = 9
=> 9b - 3 = 9
=> 9b = 9 + 3
=> 9b = 12
=> b = 12/9
=> b = 4/3 (Answer)
Hence ,
Required value of b is 4/3 .
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Question 3 :-
Given equation : 2x + 3y = 18
Answer : Infinitely many solutions
Reason :
• If a system contains only one equation , then it has infinitely many solutions .
• A straight line has infinitely many solutions as infinitely many points lies on it .
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Question 4 :-
Given equation : 3x - 4y = 12
If x = 0 , then
=> 3x - 4y = 12
=> 3•0 - 4y = 12
=> 0 - 4y = 12
=> -4y = 12
=> y = 12/-4
=> y = -3
If y = 0 , then
=> 3x - 4y = 12
=> 3x - 4•0 = 12
=> 3x = 12
=> x = 12/3
=> x = 4
Hence ,
(0,-3) and (4,0) are two solutions of the given equation .
• The equation has infinitely many solutions as Infinitely many points lies on it .
• A system containing only one equation has infinitely many solutions .