Toán Lớp 6: Tìm x, biết:
a) x – 10 = – 65 b) 15.(x – 4) = 45
c) -125 + (x + 125) = – 25 d) 2.2^x = 2^8
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Toán Lớp 6: Tìm x, biết:
a) x – 10 = – 65 b) 15.(x – 4) = 45
c) -125 + (x + 125) = – 25 d) 2.2^x = 2^8
Comments ( 2 )
Giải đáp và lời giải
a) x-10=-65
=>x=-65+10
=>x=-55
Vậy x=-55
b) 15.(x-4)=45
=>x-4=45:15
=>x-4=3
=>x=3+4
=>x=7
Vậy x=7
c) -125+(x+125)=-25
=>x+125=-25-(-125)
=>x=-25+125-125
=>x=-25+0
=>x=-25
Vậy x=-25
d) 2.2^x=2^8
=>2^(x+1)=2^8
=>x+1=8
=>x=8-1
=>x=7
Vậy x=7
a)x – 10 = -65
<=>x = -65 + 10
<=>x = -55
Vậy x = -55
b)15 . (x – 4) = 45
<=>x – 4 = 45 : 15
<=>x – 4 = 3
<=>x = 3 + 4
<=>x = 7
Vậy x = 7
c)-125 + (x + 125) = -25
<=>x + 125 = -25 – (-125)
<=>x + 125 = 100
<=>x = 100 – 125
<=>x = -25
Vậy x = -25
d)2.2^{x} = 2^{8}
<=>2^{x} = 2^{8} : 2
<=>2^{x} = 2^{7}
<=>x = 7
Vậy x = 7