Wyznacz wzór funkcji liniowe f, która spełnia podane warunki. a) f(2)=0 i f(0)=4 b)f(5/2)=1/4 i f(2)=-1 Pomocy!!
y = f(x) = a x + b
a)
f(2) = 0 czyli a*2 + b = 0
f(0) = 4 czyli a*0 + b = 4 --> b = 4
--------------
2a + b = 0
b = 4
2a + 4 = 0
2a = - 4 / : 2
a = - 2
zatem
y = f(x) = - 2 x + 4
=============================
b)
f(5/2) = 1/4 , czyli a*(5/2) + b = 1/4
f(2) = - 1, czyli a*2 + b = - 1
(5/2)a + b = 1/4
2a + b = - 1
------------------- odejmujemy stronami
2,5 a - 2a = 1/4 - (-1)
0,5 a = 1/4 + 1
(1/2) a = 5/4 / * 2
a = 2,5
======
b = -1 - 2a = - 1 - 2*(2,5) = - 1 - 5 = -= 6
b = - 6
y = f(x) = 2,5 x - 6
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y = f(x) = a x + b
a)
f(2) = 0 czyli a*2 + b = 0
f(0) = 4 czyli a*0 + b = 4 --> b = 4
--------------
2a + b = 0
b = 4
--------------
2a + 4 = 0
2a = - 4 / : 2
a = - 2
zatem
y = f(x) = - 2 x + 4
=============================
b)
f(5/2) = 1/4 , czyli a*(5/2) + b = 1/4
f(2) = - 1, czyli a*2 + b = - 1
--------------
(5/2)a + b = 1/4
2a + b = - 1
------------------- odejmujemy stronami
2,5 a - 2a = 1/4 - (-1)
0,5 a = 1/4 + 1
(1/2) a = 5/4 / * 2
a = 2,5
======
b = -1 - 2a = - 1 - 2*(2,5) = - 1 - 5 = -= 6
b = - 6
======
zatem
y = f(x) = 2,5 x - 6
=========================