Question

Please solve 5,6,7,8 with step by step explanation

Answer 1

Explanation:

7) a - 4b -c = -20 -------------(I)

3c = -6 ------------------(II)

2a +5c = -22 ---------------(III)

3c = -6 {Divide both sides by 3}

c = -6/3

c = -2

Plugin c = -2 in equation (III)

2a + 5c = -22

2a + 5*(-2) = -22

2a - 10 = -22

2a = -22 + 10

2a = -12

a = -12/2

a = -6

Plugin a = -6 and c = -2 in equation (I)

a - 4b -c = -20

-6 - 4b -(-2) = -20

-6 - 4b + 2 = -20

-4b - 4 = -20

-4b = -20 + 4

-4b = -16

b = -16/4

b= -4

8) b = 2a - 9 -----------(I)

3a - 3c = 21 -------------(II)

c = a -5b- 22

-a + 5b + c = -22 -----------(III)

Multiply equation (III) by 3 and then add to equation(II)

(III)*3 -3a + 15b + 3c = -66

(II) 3a + 0b - 3c = 21 {Now add}

15b = -45 {Divide both sides by 15}

b = -45/15

b = -3

Plugin b = -3 in equation (I)

b = 2a - 9

-3 = 2a - 9 {Add 9 to both sides}

-3 +9 = 2a

2a = 6 {Divide both sides by 2}

a = 6/2

a = 3

Plugin a = 3 in equation(II)

3a - 3c = 21

3*3 - 3c = 21

9 - 3c = 21 {subtract 9 from both sides}

-3c = 21 - 9

-3c = 12 {Divide both sides by 2}

c = 12/-3

c = -4