Question

Urgente!

a) x² - 8x +12 = 0
b) x² - 8x +15 = 0
c) x² - 100 = 0
d) x² - 8x = 0
e) x² - 36 = 0
f) x² - 7x +6 = 0
g) x² -5x = 0
h) x² - 49 = 0
i) x² - 9x +20 = 0
j) x² - 10x = 0

Answer 1

Olá,

Resolução

A)

$x^{2} -8x+12=0\\delta= b^{2} -4.a.c\\delta= -8^{2}.- 4.1 .12\\delta = 64-48\\delta= 16\\\\x1=\frac{8+4}{2} = \frac{12}{2} = 6 \\\\x2= \frac{8-4}{2} = \frac{4}{2} = 2$

S: {6,2}

B)

$x^{2} -8x+15=0\\\\delta= b^{2} -4.a.c\\delta= (-8)^{2} -4.1.15\\delta= 64 - 60\\delta= 4\\\\x1= \frac{8+2}{2} = \frac{10}{2} =5\\\\x2= \frac{8-2}{2}=\frac{6}{2} =3$

S: {5,3}

C)

$x^{2} -100=0\\\\x^{2} =100\\x^{2}=\sqrt{100} \\x= 10$

X = 10

D)

$x^{2} -8x=0\\\\\frac{8+8}{2} = \frac{16}{2} = 8$

S: {0,8}

E)

$x^{2} -36=0\\\\x^{2} =36\\x=\sqrt{36} \\x=6$

X= 6

F)

$x^{2} -7x+6=0\\\\delta=( -7)^{2} .-4.1.6\\delta= 49-24\\delta= 25\\\\x1= \frac{7+5}{2} = \frac{12}{2} = 6\\\\x2= \frac{7-5}{2} = \frac{2}{2}=1$

S: {6,1}

G)

$x^{2} -5x=0\\\\\frac{5+5}{2}= \frac{10}{2} = 5$

S: {0,5}

H)

$x^{2} -49=0\\x^{2} =49\\x=\sqrt{49} \\\\x=7$

I)

$x^{2} -9x+20=0\\\\delta= (-9)^{2} - 4.1.20\\delta= 81-80\\delta= 1\\\\x1= \frac{9+1}{2} = \frac{10}{2} = 5\\\\x2= \frac{9-1}{2} = \frac{8}{2} =4$

S: {5,4}

J)

$x^{2} -10x=0\\\\x= \frac{10+10}{2} = \frac{20}{2} = 10$

S: {0,10}