when do i flip the sign of inequalities?
i know that its one dividng or multiplying by negative but im confused.
which equation would you have to slip the sign in?
1) -2x<20
or
2) 2x<20
so which problem would i have to switch the sign in?
thank youuu (:
2007-09-20 13:15:42 · 7 answers · asked by gleek. 3 in Science & Mathematics ➔ Mathematics
Question 1
Multiply both sides by - 1 and you have to invert inequality sign:-
2 x > - 20
x > - 10
Question 2
2x < 20
x < 10
2007-09-22 09:09:42 · answer #1 · answered by Como 7 · 1⤊ 0⤋
You have to flip the inequality when multiplying (or dividing) by a negative number.
consider -2x < 20
If x is 8 then
-2 (8) < 20
-16 < 20
true
now if you don't flip the sign
-2x < 20
x < -10
8 < -10
false
Do you see why?
2007-09-20 13:20:04 · answer #2 · answered by gitter1226 5 · 1⤊ 0⤋
When multiplying OR DIVIDING both sides by negatives, you flip the inequality; you flip it in number 1, as you divide by NEGATIVE 2
you're welcooooome (:
2007-09-20 13:20:19 · answer #3 · answered by Insert nickname here 2 · 0⤊ 0⤋
If one sign or both signs are negative, if you change signs of both, the inequality will change as well.
you're solving for x, so you change signs
-2x < 20
becomes 2x > -20 (changing both signs changes the inequality)
If it were 3x < -20
becomes x < -20/3
if a > b, -a < -b : if a < b, -a > -b
2007-09-20 13:27:34 · answer #4 · answered by cidyah 7 · 0⤊ 0⤋
the first one
anytime you multiply or divide by a negative number, you change the direction of the sign
2007-09-20 13:22:15 · answer #5 · answered by bluekitty1541 4 · 0⤊ 0⤋
the first one
2007-09-20 13:20:05 · answer #6 · answered by sfroggy5 6 · 0⤊ 0⤋
u would flip it in the first sign
2007-09-20 13:19:24 · answer #7 · answered by confused girl 1 · 0⤊ 0⤋