Question

REZOLVATI IN R
a)$\frac{7}{2}x- \frac{21}{2} =0$
b)√5x-7=3
c) (x+2)(x+3)=(x-3)(x-12)
d)$\frac{x-2}{x+4} = \frac{3}{5}$
e)x ²-3x=0
f)(x-3)(x-1)(x+1)=0
g)7|x|= 4|x|-9
h) |x²-16|+|(x-4)(x+5)|=0
i)$\sqrt{ x^{2} -14x+49} + \sqrt{(7-x) ^{2} } =0$
va rog ajutati.ma ....
dau coroana.. :)

Answer 1

a)7x-21=0
7x=21 =>x=3

b)√5x=7+3
√5x=10 =>x=10√5/5=2√5

c)x²+5x+6=x²-15x+36
5x+15x=36-6
20x=30 =>x=3/2

d)5x-10=3x+12
5x-3x=12+10
2x=22 =>x=11

e)x²=3x =>x=3

f)(x-3)(x²-1)=0
x₁=3, x₂=1, x₃=-1

g)7x=4x-9
3x=-9 =>x=-3

h)x²-16+x²+x-20=0
2x²+x-36=0
Δ=1+4·2·36
Δ=289
√Δ=17
x₁=(-1-17)/4=(-18)/4=(-9)/2
x₂=(-1+17)/4=16/4=4

i)x²-14x+49+7-x=0
x²-15x+56=0
Δ=225-4·56
Δ=1
√Δ=1
x₁=(15-1)/2=7
x₂=(15+1)/2=8