Solve the system using addition.

Question

x-4.7y=17.1 x-2.4y=-10.2

Answer 1

x-4.7y = 17.1

x-2.4y =-10.2

2 equations 2 unknowns,

solve by substitution elimination or matrix alebra, or use a graphing calculator and graph the two lines and their intersection point it the solution. use an online or hand held calculator

that point is(x,y) = (-38.896, -11.957)

x= -38.896

y= -11.957

or try substitution/elimination

subtract to eliminate x and solve for y

subtract 2nd equation from 1st. when you subtract a negative number change it to + and add it

-4.7y -(-2.4y) = -4.7y+2.4y = -2.3y, 17.1-(-10.2) = 17.1+10.2= 27.3, x-x=0

0 -2.3y = 27.3

y= -6.9/27.3

y= about -0.25

substitute -6.9/27.3 for y and solve for x

x-2.4y =-10.2

x = -10.2+2.4(-6.9/27.3)

x= -10.2+ 2.4(-6.9/27.3) = -10.2-16.56/27.3 = about - 10.8066

x=about -10.8

check the answers. plug in those two values into the original two equations and see if they work

x-4.7y

= about -10.8-4.7(-.25)

=10.8 +1.2

= 12 which doesn't= 17.3,

there's an arithmetic mistake somewhere above

go with the graphing solution (-38.896, -11.957) = about (-39, -12)

x-4.7y

= -39+4.7(12)

= -39+56.4

= 17.4 which is close enough to 17.3 given rounding approximations

x-2.4y

= -39+2.4(12)

= -39+28.8

=-10.2 = exactly what is given in the 2nd equation