Toán Lớp 7: cho hàm số y = f(x) = 2x – 1 a) tính f(2) , f(3) b) tìm x để f(x) = 0
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Toán Lớp 7: cho hàm số y = f(x) = 2x – 1 a) tính f(2) , f(3) b) tìm x để f(x) = 0
Comments ( 2 )
y = f(x) = 2x – 1
a)
f(2) = 2. 2 – 1 = 4 – 1 = 3
f(3) = 2. 3 – 1 = 6 – 1 = 5
b)
f(x) = 0
<=> 2x – 1 = 0
<=> 2x = 0 + 1
<=> 2x = 1
<=> x = 1 : 2
<=> x = 1/2
$Vậy$ x = 1/2
a) f( 2 ) = 2 . 2 – 1 = 4 – 1 = 3
f( 3 ) = 2 . 3 – 1 = 6 – 1 = 5
b) Ta có : f( x ) = 0
⇒ 2x – 1 = 0
⇒ 2x = 0 + 1
⇒ 2x = 1
⇒ x = 1 : 2
⇒ x = 1/2
Vậy , x = 1/2 .