Sinxcosx=√3/4
sin2x=√3/2
2x=(-1)^N π/3+πN
x=(-1)^n π/6+π/2*n
3а+3*1,5=31
3а*1,5=31-3
4'5а=29
а=29:4,5=290:457
а=8
Bn=b1q^n-1=b1*3^n-1=567
b1*q^n-1=7^3^4
b1=7
n-1=4⇒n=5
S5=7*(243-1)/(3-1)=7*242/2=7*121=847
+ - +
______[- 2]_________[2]_______
/////////////// /////////////////
/////////////////////////
______________[1]____________
Ответ : 1 ∪ [2 ; + ∞)
<span>а) 3√20-3√45+4√5 = 3*√4*√5 - 3*√9*√5 +4*√5 = 6√5 - 9√5 + 4√5 = √5</span>
<span><span>б) (1+√3)² = 1 + 2√3 +(√3)² = 1 + 2√3 +3 = 4 + 2√3 или 2(2 + √3)</span></span>
<span><span><span>в) (√7-2)(√7+2) = (√7)² - 2² = 7 - 4 = 3</span></span></span>