Answer:
3a + 18
Step-by-step explanation:
Using linear combination method to solve the system of equations 3x - 8y = 7 and x + 2y = -7 is (x, y) = (-3, -2)
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Given that, a system of equations are:
3x – 8y = 7 ⇒ (1) and x + 2y = - 7 ⇒ (2)
We have to solve the system of equations using linear combination method and find their solution.
Linear combination is the process of adding two algebraic equations so that one of the variables is eliminated. Addition or subtraction can be used to perform a linear combination.
Now, let us multiply equation (2) with 4 so that y coefficients will be equal numerically.
4x + 8y = -28 ⇒ (3)
Now, add (1) and (3)
3x – 8y = 7
4x + 8y = - 28
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7x + 0 = - 21
7x = -21
x = - 3
Now, substitute "x" value in (2)
(2) ⇒ -3 + 2y = - 7
2y = 3 – 7
2y = - 4
y = -2
Hence, the solution for the given two system of equations is (-3, -2)
U+xy
On replacing for u, x and y.
=9+9*7
=9+63
=72
