Simplify the following algebraic expression and find the value when x

1.	Simplify the following algebraic expression and find the value when x = 3, a = -1 and b = -2(i) 3x – 5 – x +9(ii) 2 – 8x + 4x +4(iii) 3a + 5 – 8a +1(iv) 10 – 3b – 4 – 5b(v) 2a – 2b – 4 – 5 + a
Answer» (i) 3x – 5 – x + 9 = 2x +4 Put x = 3 2x + 4 = 2(3) + 4 = 6 +4 = 10 (ii) 2 – 8x + 4x + 4 = 6 – 4x Put x = 3 6 – 4x = 6 – 4(3) = 6 – 12 = -6 (iii) 3a +5 – 8a +1 = -5a + 6 Put a = -1 -5a + 6 = -5( -1) +6 = 5 + 6 = 11 (iv) 10 – 3b – 4 – 5b = 6 – 8b Put b = -2 6 – 8b = 6 – 8(-2) = 6 + 16 = 22 (v) 2a – 2b – 4 – 5 + a= 3a – 2b – 9 Put a = – 1 and b = -2 3a – 2b – 9 = 3(-1) – 2(- 2) – 9 = – 3 + 4 – 9 = -8

Simplify the following algebraic expression and find the value when x = 3, a = -1 and b = -2(i) 3x – 5 – x +9(ii) 2 – 8x + 4x +4(iii) 3a + 5 – 8a +1(iv) 10 – 3b – 4 – 5b(v) 2a – 2b – 4 – 5 + a

Answer»

(i) 3x – 5 – x + 9 = 2x +4
Put x = 3
2x + 4 = 2(3) + 4 = 6 +4 = 10

(ii) 2 – 8x + 4x + 4 = 6 – 4x
Put x = 3
6 – 4x = 6 – 4(3) = 6 – 12 = -6

(iii) 3a +5 – 8a +1 = -5a + 6
Put a = -1
-5a + 6 = -5( -1) +6
= 5 + 6 = 11

(iv) 10 – 3b – 4 – 5b = 6 – 8b
Put b = -2
6 – 8b = 6 – 8(-2)
= 6 + 16 = 22

(v) 2a – 2b – 4 – 5 + a= 3a – 2b – 9
Put a = – 1 and b = -2
3a – 2b – 9 = 3(-1) – 2(- 2) – 9
= – 3 + 4 – 9 = -8