Toán Lớp 6: tìm số nguyên x biết:
a)$x+8=6$
b)$39-x=45$
c)$x+(-35)=27$
d)$(-45)-x=-15$
e)$210-5.(x-9)=195
g) $x^{2}=4$
i) $2x^{3}-6=10$
f)$450:[41-(2x+5)]=3^{2}.5$
h) $x^{3}-1=7$
k) $2x^{2}-8=10$
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Toán Lớp 6: tìm số nguyên x biết:
a)$x+8=6$
b)$39-x=45$
c)$x+(-35)=27$
d)$(-45)-x=-15$
e)$210-5.(x-9)=195
g) $x^{2}=4$
i) $2x^{3}-6=10$
f)$450:[41-(2x+5)]=3^{2}.5$
h) $x^{3}-1=7$
k) $2x^{2}-8=10$
Comments ( 2 )
$a)x+8=6$
$x=6-8$
$x=-2$
$b)39-x=45$
$x=39-45$
$x=-6$
$c)x+(-35)=27$
$x=27-(-35)$
$x=62$
$d)(-45)-x=(-15)$
$x=(-45)-(-15)$
$x=-30$
$e)210-5.(x-9)=195$
$5.(x-9)=210-195$
$5.(x-9)=15$
$x-9=15:5$
$x-9=3$
$x=3+9$
$x=12$
$g)x^2=4$
$x=2$
$i)2³-6=10$
$8-6=10$
Giải đáp:
a)
x+8=6
⇒x=6-8
⇒x=-2
Vậy x=-2
b)
39-x=45
⇒x=39-45
⇒x=-6
Vậy x=-6
c)
x+(-35)=27
⇒x-35=27
⇒x=27+35
⇒x=62
Vậy x=62
d)
(-45)-x=-15
⇒x=-45-(-15)
⇒x=-45+15
⇒x=-30
Vậy x=-30
e)
210-5.(x-9)=195
⇒5.(x-9)=15
⇒x-9=3
⇒x=12
Vậy x=12
g)
x^2=4
⇒x^2=(+-2)^2
⇒x=+-2
Vậy x∈{2;-2}
i)
2x^(3)-6=10
⇒2x^3=16
⇒x^3=8
⇒x^3=2^3
⇒x=2
Vậy x=2
f)
450:[41-(2x+5)]=3^(2).5
⇒450:(41-2x-5)=45
⇒-2x+36=10
⇒-2x=-26
⇒x=13
Vậy x=13
h)
x^(3)-1=7
⇒x^3=8
⇒x^3=2^3
⇒x=2
Vậy x=2
k)
2x^(2)-8=10
⇒2x^(2)=18
⇒x^2=9
⇒x^2=(+-3)^2
⇒x=+-3
Vậy x∈{3;-3}