Question

Select ALL the expressions that have the same value as 9s

1. 9+s
2. 9*s
3. 3s + 6s
4. 3(3s)
5. s(5+4)
6. 3s * 3s
7. s+s+s+s+s+s+s+s+s2. 3s+2t=-4-6s-10t=-7What’s the value of s ?

Answer 1

2, 3, 4, 5, and 7 are the correct expressions that have the same values as 9s

Explanation

Using Simultaneous equation

3s + 2t = -4 .............................................(1)

-6s - 10t = -7 .............................................(2)

multiply equation 1 by 2 and multiply equation 2 by 1:

equ 1 x 2: 6s + 4t = -8 ...............................(3)

equ 2 x 1: -6s -10t = -7 ................................(4)

Add equation 3 and 4 together

0s -6t = - 15

Divide through by -6:

`\begin{gathered} t\text{ = }(-15)/(-6) \\ t\text{ = }(5)/(2) \end{gathered}`

substitute the value of t into equation 1:

`\begin{gathered} 3s\text{ + 2t = -4} \\ 3s\text{ + 2(}(5)/(2))\text{ = -4} \\ 3s\text{ + 5 = -4} \\ 3s\text{ = -4 -5} \\ 3s\text{ = -9 } \\ s\text{ = }(-9)/(3) \\ s\text{ = -3} \\ \end{gathered}`

Now solving for the expression that has the same value as 9s:

Note: 9s = 9(-3) = -27

1. 9 + s = 9 - 3 = 6

2. 9 * s = 9 * -3 = -27

3. 3s + 6s = 3(-3) + 6(-3) = -9 -18 = -27

4. 3(3s) = 9s = 9(-3) = -27

5. s(5 + 4) = s(9) = -3(9) = -27

6. 3s * 3s = 3(-3) * 3(-3) = -9 * -9 = 81

7. s+s+s+s+s+s+s+s+s = -3-3-3-3-3-3-3-3-3 = -27

Hence, 2, 3, 4, 5, and 7 are the correct expressions that have the same values as 9s.