Question

x^2-7x = 0
substitue x=7 into the equatiopn and explain why this shows that x=7 is the solution.

ok so i do this: if x=7 then the equation becomes
7^2-49=0
7^2=49
49-49=0
so x=7 is correct (is that explanation enough?)

now i have to write out a complete solution to the orginal equation - i thought i had already done that above, could someone help me out please!

Answer 1

<b>the solution:</b>
x^2 - 7x = 0
x(x-7) = 0
so x = 0 or x = 7

<b>the check:</b>
if x = 0
LS = 0^2 - 7(0) = 0
RS = 0
so x = 0

if x = 7
LS = 7^2 - 7(7) = 49-49 = 0
RS = 0
so x = 7

x = 0 or x = 7


(The correct way to verify a solution is to show for the given value that the original left side (LS) is equal to the original right side (RS) of the equation. )