Question

buna. ma ajutati va rog la doua trei ecuatii. recunosc, nu prea ma incanta matematica :D
3X la puterea 2 =27

7X la puterea 2 =64/7

X la puterea 2 =2, (3)

(3X + 1) la puterea 2 - 20=101
Multumesc mult!!

Answer 1

3x² =27
x²=9
x=+/- 3

7x²=64/7
x²=64/49
x=+/- 8/7

x² =2, (3)
2,(3)=(23-2)/9=21/9=7/3
x²=7/3
x=+/- √7/√3

(3x + 1)² - 20=101 
(3x + 1)²=121 

3x+1=11
x=10/3

3x+1=-11
x=-4

Answer 2

3x²=27
x²=27/3
x²=9
x₁=√9=3
x₂=-√9=-3

7x²=64/7
7·7x²=64
49x²=64
x²=64/49
x₁=√64/49=8/7
x₂=-8/7

x²=2,(3)
x²=(23-2)/9
x²=21/9=simplif cu 3=7/3
x₁=√7/√3=√21/3
x₂=-√21/3

(3x+1)²-20=101
9x²+6x+1-20=101
9x²+6x-19-101=0
9x²+6x-120=0                         :3
3x²+2x-40=0
Δ=4+480=484
x₁=(-2+√484)/6=(-2+22)/6=20/6=10/3
x₂=(-2-22)/6=-24/6=-4