i. First simplify the following expressions, then determine the value of the expression by substituting a = 7.

a. 13a+2a—5a b. 3a+7a
b. 3a+ 7a
c. 17 +5a+3a d. 6a—a+2
d. 6a-a+2

1 answer

a. 13a+2a-5a

Combine like terms:
13a + 2a - 5a = 15a - 5a

Simplify further:
15a - 5a = 10a

Substitute a = 7:
10(7) = 70

b. 3a + 7a

Combine like terms:
3a + 7a = 10a

Substitute a = 7:
10(7) = 70

c. 17 + 5a + 3a

Combine like terms:
5a + 3a = 8a

Add the constants:
17 + 8a

Substitute a = 7:
17 + 8(7) = 17 + 56 = 73

d. 6a - a + 2

Combine like terms:
6a - a = 5a

Add the constants:
5a + 2

Substitute a = 7:
5(7) + 2 = 35 + 2 = 37