Question

Solve x + 2y = 50

-2x + 3y = 40
5x + 5y + 5z = 300

Answer 1

Can use elimination on the first two equations by multiplying the first equation by 2 and adding it to the second equation; that will let you solve for y. Put that value of y into the first equation to get x. With values for x and y, put both into the third equation to get z.

Answer 2

Also, the third equation may be divided by 5 to reduce.

Answer 3

x + 2y = 50

x = 50 -2y

now put this value in second equation :
\[\large{-2(50-2y)+3y=40}\]
\[\large{-2(50)-2(-2y) + 3y = 40}\]
\[\large{-100+4y+3y=40}\]
\[\large{7y = 140}\]
\[\large{y = \frac{140}{7}=20}\]

Answer 4

now as we derived that ... x = 50-2y

put y =20

x = 50 - 2(20) = 50 - 40 = 10

now put this in third equation :
\[\large{5x+5y+5z=300}\]
\[\large{5(10)+5(20)+5z=300}\]
\[\large{50+100+5z=300}\]
\[\large{5z=300-150}\]

Answer 5

what do you get for z ?

Answer 6

@DFlame28 please reply...
what is z if 5z = 150..