Question

7 Work out the value of each expression.
a x + 7 when x=-12
b 3x - 4y when x= 2 and y=7
C 3n+ 1 when n= -6
d 30-5k when k= -2
e x - 10 when x= 3
f 4y when y= 2​

Answer 1

Step-by-step explanation:

1.Since, the point (x = 3, y = 4) lies on the equation 3y = ax + 7, then the equation will be , satisfied by the point.

Now, put x = 3 and y = 4 in given equation, we get

3(4) = a (3)+7

⇒ 12 = 3a+7

⇒ 3a = 12 – 7

⇒ 3a = 5

Hence, the value of a is 5/3.

Answer 2

Answer:

a) x + 7 when x=-12

=> (-12)+7 = -5

b) 3x - 4y when x= 2 and y=7

=> 3(2) - 4(7)

=>6 - 28 = -22

c) 3n+ 1 when n= -6

=>3(-6)+ 1 => -18 + 1 =>-17

d) 30-5k when k= -2

=>30 - 5(-2) => 30 + 10 => 40

e) x - 10 when x= 3

=> 3 - 10 => -7

f) 4y when y= 2

=> 4(2) => 8

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