Page 70 - Math Smart - 7

So, the solution of the equation \sx = 2.
To solve equations,
In other words, .v = 3 satisfies the equation a + 2 = 5.
you use the inverse
operation. We can also use number pairs to help us find
-2 is the inverse of +2 the solution. So, a = 3

We can use substitution to check if the value of the variable is correct.

Example 2

Solve the following equations for x. Then check your answers.

O a + 8 = 25 Solution

A + 8 = 25
x + 8- 8 = 25-8 Subtract 8 from both sides of the
/ LHS = 17 + 8 = 25
So, a: = 17. equation (- 8 is the inverse of + 8)

@ a-7 = Solution
9
a-7 =
9
a-7 + 7 = 9 + 7 Add 7 to both sides of the
So, a = 16. equation (+ 7 is the inverse of - 7) / LHS = 16-7 = 9

© 3a: = 24 Solution

3x = 24
Divide each side of the equation
3 3 by 3 (the inverse of multiply by 3
So, X = 8. is divide by 3) / LHS = 3 X 8 = 24

© ^=7 Solution
.Y
5 =7
5 xi = 5 X7 Multiply each side of the equation
/ lHS= 35 = 7
So, X = 35. by 5 (the inverse of divide by 5 is ^ 5
multiply by 5)

Check My
Understanding

O Solve the equations by finding the values of the unknowns.
a) X + 9 = 52 b) a + 7 = 16 c) y-8 = 2
d) z + 10 = 25 e) 15 = q - 11 f) 40 = b + 25
O Solve the equations.
a) 5x = 30 b) f =12 c) 6y= 18
d) y = 12 e) 48 = 12z f) 20 = .'
-i\
Find the value of each unknown,
a) m + 15 = 30 b) 12 = a-5 C) d) 64 = 8m
* =2
e) ^=7 f) g) 12q = 108 h) 75 = c + 25

UNITS Introduction to Algebra and Equations