+∞
∫ x · e ^(-x² ) dx = / The substitution: u = - x², x d x = - du / 2
-∞
+∞
= - 1/2 · ∫ e ^(u) du = - 1/2 · e ^(-x²) /
- ∞
e^(-∞) = 1 / e^(∞)
= -1/2 · [ 1/ e^(∞) - 1/ e^(∞) ] = -1/2 · ( 0 - 0 ) = 0
3(x+6)>8-(x-7)
3x+18>8-x+7
2x+18>15
2x>-3
X>-3/2
So he bought the $120 game with $82 and 2 equally priced game. This can be changed to an equation: 120= 82+2X. The X represents the cost of the used game.
120= 82+2X
-82 -82
——————-
38= 2X
38= 2X
Divide by 2 on both sides
X= 19
Absolute value is h<span>ow far a number is from zero.
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For example |-4|=4 or |98| =98.
