Answer:
x = —4, y = 3
Step-by-step explanation:
-3x + 2y = 18 (1)
-9x - 5y =21 (2)
To solve by eliminating, the coefficients of either x or y must be the same in both equation.
Now let us make the coefficient of x in both equation to be the same. To do this, multiply equation (1) by the coefficient of x in equation (2) ie —9, and multiply equation (2) by the coefficient of x in equation (1) ie —3 this is illustrated below :
—9 ( —3x + 2y = 18)
27x — 18y = — 162 (3)
—3 ( —9x — 5y = 21)
27x + 15y = —63 (4)
Now, subtract equation 4 from equation 3
27x — 18y = — 162
— (27x + 15y = —63)
—33y = —99
Divide both side by —33
y = —99/—33
y = 3
Now we substitute the value of y into any of the equation to obtain x. In this case, let use equation 4
27x + 15y = —63
27x + 15(3) = —63
27x + 45 = —63
Collect like terms
27x = —63 —45
27x = —108
Divide both side by 27
x = —108/27
x = —4
Therefore, x = —4, y = 3
