Tìm x ∈ Z
a, 71 – ( 33 + x ) = -26
b, (-9) x (120 – x ) = 450
c, 280 – 9x = 80 + x
Tìm x ∈ Z a, 71 – ( 33 + x ) = -26 b, (-9) x (120 – x ) = 450 c, 280 – 9x = 80 + x
By Anna
By Anna
Tìm x ∈ Z
a, 71 – ( 33 + x ) = -26
b, (-9) x (120 – x ) = 450
c, 280 – 9x = 80 + x
Đáp án:
`a, 71 – ( 33 + x ) = -26`
`33 + x = 71 – (-26)`
`33 + x = 71 + 26`
`33 + x = 97`
`x = 97 – 33`
`x = 64`
Vậy `x = 64`
b, `(-9) × (120 – x ) = 450`
`120 – x = 450 : (-9)`
`120 – x = (-50)
`x = 120 – (-50)`
`x = 120 + 50`
`x = 170`
Vậy `x = 170`
c, `280 – 9x = 80 + x`
`280 – 80 = 9x + x`
`10x = 200`
`x = 200 : 10`
` x = 20`
Vậy `x = 20`
a,$71-(33+x)=-26$
`⇔33+x=71-(-26)`
`⇔33+x=97`
`⇔x=64`
b) `(-9)×(120-x)=450`
`⇔120-x=450:(-9)`
`⇔120-x=-50`
`⇔x=170`
c)`280-9x=80+x`
`⇔280-80=9x+x`
`⇔200=10x`
`⇔x=200:10`
`⇔x=20`