0 = 0⁰
п/2 = 30⁰
п = 180⁰
3п/2 = 270⁰
2п = 360⁰
1/3:21/5<span>+1,4х=5/7:9/5-0,6х
5/63+1,4х=25/63-0,6х
1,4х+0,6х=25/63-5/63
2х=20/63
х=20/126=10/63</span>
1)11x^2-6x-27-8x2+6x=0
3x^2-27=0
3x^2=27
x^2=9
x1=3
x2=-3
Cos2a+2(sina*cos(п/6)+cosa*sin(п/6)*(sina*cos(п/6)-cosa*sin(п/6))=cos2a+2(sin^2(a)*cos^2(п/6)-cos^2(a)*sin^2(п/6))=cos2a+2(0.75*sin^2(a)-0.25*cos^2(a))=cos^2(a)-sin^2(a)+1.5*sin^2(a)-0.5*cos^2(a)=0.5(sin^2(a)+cos^2(a))=0.5
(3х + 4)(3х - 4) = (3х)² - 4² = 9х² - 16
(4х + 5)(4х + 5) = (4х + 5)² = (4х)² + 2*4х*5 + 5² = 16х² + 40х + 25
(2х - 3)(2х - 3) = (2х - 3)² = (2х)² - 2*2х * 3 + 3² = 4х² - 12х + 9
(2х + 1)(4х² - 2х + 1) = (2х + 1)( (2х)² - 2*х*1 + 1²) = (2х)³ + 1³ = 8х³ + 1
(х - 2)(х² + 2х + 4) = (х - 2)(х² + х*2 + 2²) = х³ - 2³ = х³ - 8
51² = (50 + 1)² = 50² + 2*50*1 + 1² = 2500 + 100 + 1= 2601
39² = (40 - 1)² = 40² - 2*40*1 + 1² = 1600 - 80 + 1 = 1521
103² = (100 + 3)² = 100² + 2*100*3 + 3² = 10000 + 600 + 9 = 10609
78² = ( 80 - 2)² = 80² - 2*80*2 + 2² = 6400 - 320 + 4 = 6084