Question

Find the value of the following expressions given that: a = -2, b =4 and c = -1
a)7a + b - c
b) 3c - b + 2a

Answer 1

Answer:

a) 7a + b - c

putting values

= 7(-2) + 4 - (-1)

= -14 + 4 + 1

= 10+1

= 11 answer

Step-by-step explanation:

b) 3c - b + 2a

putting values

= 3(-1) - 4 + 2(-2)

= -3 -4 -4

= -11 answer

Answer 2

Answer :-

• a) 7a + b - c = -9
• b) 3c - b + 2a = 5

Step-by-step explanation :-

$\bf{a) \: \: \: 7a + b - c}$

$\tt{ \mapsto \: 7a + b - c \: \: \: \: \: \: ...putting \: the \: values} \\ \\ \\ \tt{ \mapsto \: 7 \times ( - 2) + 4 - ( - 1)} \\ \\ \\ \tt{ \mapsto \: - 14 + 4 - ( - 1)} \\ \\ \\ \tt{ \mapsto \: - 10 - ( - 1)} \\ \\ \\ \tt{ \mapsto \: - 10 + 9} \\ \\ \\ \frak{ \pink{ \mapsto \: - 9}} \: \: \: \: \: \: \bigstar$

$\bf{b) \: \: 3c - b + 2a}$

$\tt{ \mapsto \: 3c - b + 2a \: \: \: \: \: \: ...putting \: the \: values} \\ \\ \\ \tt{ \mapsto \: 3 \times ( - 1) + 4 - 2 \times ( - 2)} \\ \\ \\ \tt{ \mapsto \: - 3 + 4 - 2 \times ( - 2)} \\ \\ \\ \tt{ \mapsto \: 1 - (- 4)} \\ \\ \\ \frak{ \pink{ \mapsto 5}} \: \: \: \: \: \: \bigstar$

Now, Verification

$\bf{a) \: \: \: 7a + b - c = - 9} \\ \\ \\ \tt{ \mapsto \: 7 \times ( - 2) + 4 - ( - 1) = - 9} \\ \\ \\ \tt{ \mapsto \: - 14 + 4 - ( - 1) = - 9} \\ \\ \\ \tt{ \mapsto \: - 10 - ( - 1) = - 9} \\ \\ \\ \tt{ \mapsto \: - 10 + 9 = - 9} \\ \\ \\ \bf{ \mapsto \: - 9 = - 9}$

L.H.S = R.H.S

Hence, Verified !!!

$\bf{b) \: \: 3c - b + 2a = 5} \\ \\ \\ \tt{ \mapsto \: 3 \times ( - 1) + 4 - 2 \times ( - 2) = 5} \\ \\ \\ \tt{ \mapsto \: - 3 + 4 - 2 \times ( - 2) = 5} \\ \\ \\ \tt{ \mapsto \: 1 - (- 4) = 5} \\ \\ \\ \bf{ \mapsto 5 = 5}$

L.H.S = R.H.S

Hence, Verified !!!