Question

Tìm x

A, ( x - 3 ) ^2 = (-3)^2 + (-4)^2

B, -12 × ( x -5 ) + 7 × ( 3-x) = 5

C, 30 × ( x + 2) -6 × ( x-5 ) - 24 × x = 100

Answer 1

a) \(\left(x-3\right)^2\) = \(\left(-3\right)^2\) + \(\left(-4\right)^2\)

\(\left(x-3\right)^2=9+16\)

\(\left(x-3\right)^2=25\)

\(\left(x-3\right)^2=5^2\)

\(\Rightarrow x-3=5\)

\(\Rightarrow x=5+3=8\)

Vậy x = 8

Answer 2

b) -12 . (x - 5) +7 . (3 - x) = 5

-12x + 60 + 21 - 7x = 5

-12x - 7x = 5 - 60 - 21

-19x = -76

x = -76 : (-19) =4

Vậy x = 4

Answer 3

c) 30 . (x + 2) - 6 . ( x - 5) - 24x = 100

30x + 60 - 6x + 30 - 24x =100

30x - 6x - 24x = 100 - 30 - 60

0x = 10

x=10 : 0

\(\Rightarrow x\in\varnothing\)