Solve the system. What is the value of x?
y = 3x and 4x + 2y = 30
A. 3
B. -3
C. 9
D. -9

Question

Solve the system. What is the value of x?
y = 3x and 4x + 2y = 30
	A.	3
	B.	-3
	C.	9
	D.	-9

anonymous · Answer

Substitute y = 3x in second equation.

anonymous · Answer

3

ash2326 · Answer

y=3x
4x+2y=30
put y=3x in second equation
4x+2*3x=30
10x=30
x=3

mathteacher1729 · Answer

(equation ONE) y = 3x and (equation TWO) 4x + 2y = 30 Substitute y = 3x into the 2nd equation: 4x + 2(3x) = 30 simplify 4x + 6x = 30 10x = 30 x = 3 Now that you know x = 3, you can put that into the second equation 4x + 2y = 30 4(3) + 2y = 30 12 + 2y = 30 subtract 12 from both sides 2y = 18 divide by 2 y = 9 =========== So x = 3, y = 9. =========== You can see this by going to http://www.wolframalpha.com and typing plot y = 3x and 4x + 2y = 30 (note the intersection of the two lines is at (3,9). :)