Page 1
Linear Equations in Two Variables
Practice Set 1.1
Q. 1. Complete the following activity to solve the simultaneous equations.
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Answer :
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Subtracting equation (ii) from (i), we get,
(5x + 3y ) - (2x + 3y) = 9 - 125x - 2x + 3y - 3y = -33x = -3x = -1Putting the value of x in
equation (i), 5(-1) + 3y = 9-5 + 3y = 93y = 14y = 14/3
Let’s add equations (I) and (II).
Hence, x = -1 and y = 14/3 is the solution of the equation.
Q. 2 A. Solve the following simultaneous equation.
3a + 5b = 26; a + 5b = 22
Answer :
Change the sign of Eq. (II)
Page 2
Linear Equations in Two Variables
Practice Set 1.1
Q. 1. Complete the following activity to solve the simultaneous equations.
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Answer :
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Subtracting equation (ii) from (i), we get,
(5x + 3y ) - (2x + 3y) = 9 - 125x - 2x + 3y - 3y = -33x = -3x = -1Putting the value of x in
equation (i), 5(-1) + 3y = 9-5 + 3y = 93y = 14y = 14/3
Let’s add equations (I) and (II).
Hence, x = -1 and y = 14/3 is the solution of the equation.
Q. 2 A. Solve the following simultaneous equation.
3a + 5b = 26; a + 5b = 22
Answer :
Change the sign of Eq. (II)
Substituting a = 2 in Eq. (II)
? solution is (a, b) = (2, 4)
Q. 2 B. Solve the following simultaneous equation.
x + 7y = 10; 3x – 2y = 7
Answer :
Multiply Eq. I by 2 and Eq. II by 7
x=3
Substituting x= 3 in Eq. I
Page 3
Linear Equations in Two Variables
Practice Set 1.1
Q. 1. Complete the following activity to solve the simultaneous equations.
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Answer :
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Subtracting equation (ii) from (i), we get,
(5x + 3y ) - (2x + 3y) = 9 - 125x - 2x + 3y - 3y = -33x = -3x = -1Putting the value of x in
equation (i), 5(-1) + 3y = 9-5 + 3y = 93y = 14y = 14/3
Let’s add equations (I) and (II).
Hence, x = -1 and y = 14/3 is the solution of the equation.
Q. 2 A. Solve the following simultaneous equation.
3a + 5b = 26; a + 5b = 22
Answer :
Change the sign of Eq. (II)
Substituting a = 2 in Eq. (II)
? solution is (a, b) = (2, 4)
Q. 2 B. Solve the following simultaneous equation.
x + 7y = 10; 3x – 2y = 7
Answer :
Multiply Eq. I by 2 and Eq. II by 7
x=3
Substituting x= 3 in Eq. I
7y=7
y=1
? Solution is (x , y) = (3, 1)
Q. 2 C. Solve the following simultaneous equation.
2x – 3y = 9; 2x + y = 13
Answer :
Change the sign of Eq. (II)
Substituting y = 1 in Eq. (II)
2x = 13 - 12x = 12x = 6
? solution is (x, y) = (1,6)
Q. 2 D. Solve the following simultaneous equation.
5m – 3n = 19; m – 6n = –7
Page 4
Linear Equations in Two Variables
Practice Set 1.1
Q. 1. Complete the following activity to solve the simultaneous equations.
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Answer :
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Subtracting equation (ii) from (i), we get,
(5x + 3y ) - (2x + 3y) = 9 - 125x - 2x + 3y - 3y = -33x = -3x = -1Putting the value of x in
equation (i), 5(-1) + 3y = 9-5 + 3y = 93y = 14y = 14/3
Let’s add equations (I) and (II).
Hence, x = -1 and y = 14/3 is the solution of the equation.
Q. 2 A. Solve the following simultaneous equation.
3a + 5b = 26; a + 5b = 22
Answer :
Change the sign of Eq. (II)
Substituting a = 2 in Eq. (II)
? solution is (a, b) = (2, 4)
Q. 2 B. Solve the following simultaneous equation.
x + 7y = 10; 3x – 2y = 7
Answer :
Multiply Eq. I by 2 and Eq. II by 7
x=3
Substituting x= 3 in Eq. I
7y=7
y=1
? Solution is (x , y) = (3, 1)
Q. 2 C. Solve the following simultaneous equation.
2x – 3y = 9; 2x + y = 13
Answer :
Change the sign of Eq. (II)
Substituting y = 1 in Eq. (II)
2x = 13 - 12x = 12x = 6
? solution is (x, y) = (1,6)
Q. 2 D. Solve the following simultaneous equation.
5m – 3n = 19; m – 6n = –7
Answer :
Multiply Eq. II by 5
equating (I) and (III), change the sign of Eq. (III)
Adding both we get
? n = 2
Substituting n = 2 in Eq 1
? 5m - 3(2) = 19 ? 5m - 6 = 19 ? 5m = 25 ? m = 5
? Solution is (m , n) = (5, 2)
Q. 2 E. Solve the following simultaneous equation.
5x + 2y = –3; x + 5y = 4
Answer :
Multiply Eq. I by 5 and Eq. II by 2
Page 5
Linear Equations in Two Variables
Practice Set 1.1
Q. 1. Complete the following activity to solve the simultaneous equations.
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Answer :
5x + 3y = 9 ……. (i)
2x + 3y = 12 ……… (ii)
Subtracting equation (ii) from (i), we get,
(5x + 3y ) - (2x + 3y) = 9 - 125x - 2x + 3y - 3y = -33x = -3x = -1Putting the value of x in
equation (i), 5(-1) + 3y = 9-5 + 3y = 93y = 14y = 14/3
Let’s add equations (I) and (II).
Hence, x = -1 and y = 14/3 is the solution of the equation.
Q. 2 A. Solve the following simultaneous equation.
3a + 5b = 26; a + 5b = 22
Answer :
Change the sign of Eq. (II)
Substituting a = 2 in Eq. (II)
? solution is (a, b) = (2, 4)
Q. 2 B. Solve the following simultaneous equation.
x + 7y = 10; 3x – 2y = 7
Answer :
Multiply Eq. I by 2 and Eq. II by 7
x=3
Substituting x= 3 in Eq. I
7y=7
y=1
? Solution is (x , y) = (3, 1)
Q. 2 C. Solve the following simultaneous equation.
2x – 3y = 9; 2x + y = 13
Answer :
Change the sign of Eq. (II)
Substituting y = 1 in Eq. (II)
2x = 13 - 12x = 12x = 6
? solution is (x, y) = (1,6)
Q. 2 D. Solve the following simultaneous equation.
5m – 3n = 19; m – 6n = –7
Answer :
Multiply Eq. II by 5
equating (I) and (III), change the sign of Eq. (III)
Adding both we get
? n = 2
Substituting n = 2 in Eq 1
? 5m - 3(2) = 19 ? 5m - 6 = 19 ? 5m = 25 ? m = 5
? Solution is (m , n) = (5, 2)
Q. 2 E. Solve the following simultaneous equation.
5x + 2y = –3; x + 5y = 4
Answer :
Multiply Eq. I by 5 and Eq. II by 2
Change sign of Eq.(IV)
Subsituting x=–1in Eq.II
? solution is (x, y) = (–1, 1)
Q. 2 F. Solve the following simultaneous equation.
Answer :
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