Answer:
Step-by-step explanation:
1) y = 2x ----------(I)
x + y = 6 -----------(II)
Plug in y =2x in equation (II)
x + 2x = 6 {Add like terms}
3x = 6
x = 6/3
x = 2
Plugin x = 2 in (I)
y = 2*2
y = 4
Check:
LHS = x +y
= 2 + 4
= 6 = RHS
2)5x + 10y = 3 ------------(I)
x = (-1/2) y ------------(II)
Substitute x = (-1/2)y in (I)
[tex]5*\frac{-1}{2}y + 10y = 3\\\\\frac{-5}{2}y+ \frac{10*2}{1*2}y = 3\\\\\frac{-5}{2}y+\frac{20}{2}y=3\\\\\frac{-5+20}{2}y = 3\\\\\frac{15}{2}y=3\\\\ y = 3*\frac{2}{15}\\\\ y = \frac{2}{5}[/tex]
Substitute y = (2/5) in equation (II)
[tex]x = \frac{-1}{2}*\frac{2}{5}\\\\x = \frac{-1}{5}[/tex]
Check:
Substitute x and y value in equation (I)
[tex]LHS = 5*\frac{-1}{5}+10*\frac{2}{5}\\\\ = -1 + 2*2\\\\ = -1 + 4\\ = 3 = RHS[/tex]
3) y - x = 3x + 2
y = 3x + 2 + x
y = 4x + 2 ---------------(I)
2x + 2y = 14 - y
2x + 2y +y = 14
2x + 3y = 14 ------------------(II)
Substitute y = 4x + 2 in equation (II)
2x + 3(4x +2) = 14
2x + 3*4x + 3*2 = 14
2x + 12x + 6 = 14
14x + 6 = 14
14x = 14 - 6
14x = 8
x = 8/14
x = 4/7
Substitute 'x' value in (I)
[tex]y = 4*\frac{4}{7} +2\\\\y = \frac{16}{7}+2\\\\y= \frac{16}{7}+\frac{2*7}{1*7}\\\\y=\frac{16}{7}+\frac{14}{7}\\\\y=\frac{30}{7}[/tex]
Check:
[tex]LHS = 2x + 3y\\\\ = 2*\frac{4}{7}+3*\frac{30}{7}\\\\ = \frac{8}{7}+\frac{90}{7}\\\\=\frac{8+90}{7}\\\\=\frac{98}{7}\\\\=14 = RHS[/tex]
