anonymous9145
contestada

Can someone please help me with this problem? You need to find the value of x and y by using the strategy of ELIMINATION. Please show your work.
Here are the two equations:
7x + 8y = 20
7x - 2y = 29

Thanks in advance!

Respuesta :

znk

Answer:

x = 136/35; y = -⁹/₁₀

Step-by-step explanation:

(1)         7x + 8y = 20

(2)        7x – 2y = 29       Subtract (2) from (1)

                  10y =  -9        Divide each side by 10

(3)                 y =  -⁹/₁₀     Substitute (3) into (1)

      7x - 2(-⁹/₁₀) = 29

      7x + 18/10  = 29                       Subtract 18/10 from each side

      7x              =      29 - 18/10

      7x              = (290 - 18)/10

      7x              =          272/10        Divide each side by 7

        x              =           272/70

        x              =           136/35

x = 136/35; y = -⁹/₁₀

Check:

(1) 7(136/35) + 8(-⁹/₁₀) = 20

      136/5    -   72/10 = 20

      136/5    -   36/5  = 20

                      100/5  = 20

                       20      = 20

(2) 7(136/35) – 2(-⁹/₁₀)  = 29

       136/5    +    18/10 = 29

       136/5    +      ⁹/₅    = 29

                        145/5  = 29

                        29       = 29

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