Algebraic expressions: Class 7 maths video

0:00 Class 7 maths. Algebraic expressions.

0:04 Welcome to Team Calc hero training!

0:06 Today we unlock the secrets of algebraic expressions to solve real world missions.

0:13 Variables, Constants, and Terms.

0:16 A variable is a letter like x or y that represents an unknown number.

0:22 A constant is a fixed number like 5 or -12.

0:26 Try this one. Identify the terms and coefficients in 5x - 3y + 8.

0:34 Separate the expression by its operations into terms: 5x, -3y, and 8.

0:41 Identify numerical coefficients for variable terms: coefficient of x is 5, coefficient of y is -3.

0:50 Identify the constant term: 8.

0:53 So the answer is Terms are 5x, -3y, 8; coefficients are 5 and -3..

0:60 Like and Unlike Terms.

1:02 Like terms have the exact same algebraic variables with the same powers.

1:08 Unlike terms have different variables or different powers.

1:12 Try this one. Group like terms from this list: 4x, 7y, -2x, 3y, 5.

1:21 Find terms with variable x: 4x and -2x.

1:26 Find terms with variable y: 7y and 3y.

1:31 Identify remaining constant term: 5.

1:34 So the answer is (4x, -2x), (7y, 3y), and 5..

1:40 Adding and Subtracting Expressions.

1:43 To add expressions, collect like terms and add their coefficients.

1:48 To subtract an expression, change the sign of every term inside the subtracted expression.

1:54 Try this one. Add (4x + 5y) and (2x - 3y).

2:02 Write expression: (4x + 5y) + (2x - 3y).

2:07 Group like terms: (4x + 2x) + (5y - 3y).

2:13 Combine terms: 6x + 2y.

2:16 So the answer is 6x + 2y.

2:20 Finding the Value of an Expression.

2:23 To evaluate an expression, substitute the given numerical value for each variable.

2:29 Follow standard order of operations: brackets, powers, multiplication, division, addition, subtraction.

2:37 Try this one. Find the value of 4x + 7 when x = 3.

2:44 Substitute 3 in place of x: 4(3) + 7.

2:49 Multiply 4 by 3 to get 12.

2:52 Add 7 to get 19.

2:54 So the answer is 19.

2:57 Your turn. What is the constant term in 4y - 9? Pause the video, and try it.

3:06 The answer is -9.

3:08 Well done! Now try the practice and the quiz in this lesson on LearnFun.