a) The solution of the equation 9x – 8 = 19 is _______.
b)The highest power of a variable in a linear equation is _______
c)Solve: 7x – 15 = 2x + 5
d)If the cost of 1 kg of oranges is Rs. 42.50, find the cost of 3.5 kg of oranges.
e)Find the value of the expression (a
2 + 4ab) if a = - 1 and b = 2
Answers
★ Answer -:
a) The solution of the equation 9x - 8 = 19 is 3 .
9x - 8 = 19
by transposing
9x = 19 + 8
9x = 27
x = 27/9
x = 3
b) The highest power of a variable in a linear equation is 1.
Examples of linear equation =
x + 2 = 18 , y + 2y = 27 etc
c) 7x - 15 = 2x + 5
by transposing
7x - 2x = 5 + 15
5x = 20
x = 20/5
→ x = 4
d) cost of 1 kg oranges = ₹ 42.50
cost of 3.5 kg oranges = ?
by unitary method
cost of 3.5 kg oranges =
42.5 × 3.5 =
= ₹ 148.75
e) Value of 2 + 4ab when a = -1 , b = 2
by putting the values
2 + 4(-1)(2)
2 + (-4)(2)
2 - 8
= -6
★ Additional Information -:
What are variables ?
→ Variables in an equation are the things whose values can change ..
for example -:
In 9x - 8 = 19 , x is a variable as the value of x can differ in different equations .
What are constants ?
→ Constants are those things in an equation whose value remains constant or doesn't change ..
for example -:
In 9x - 8 = 19 , 8 and 19 are constants ..
Answer:
a) The solution of the equation 9x - 8 = 19 is 3 .
b) The highest power of a variable in a linear equation is 1.
c) 7x - 15 = 2x + 5
by transposing
7x - 2x = 5 + 15
5x = 20
x = 20/5
→ x = 4
d) cost of 1 kg oranges = ₹ 42.50
cost of 3.5 kg oranges =
42.5 × 3.5 =
= ₹ 148.75
e) Value of 2 + 4ab when a = -1 , b = 2
by putting the values
2 + 4(-1)(2)
2 + (-4)(2)
2 - 8
= -6