(-3.25-2.75)÷(-0.6)+0.8×(-7)= (-6)÷(- 0.6)+0.8×(-7)= 10+0.8×(-7)= 10+(-5,6)= 10-5.6= 4.4
А) 1)1÷1 7/8=1÷15/8=8/15;
2) <span>3/7×3 1/2=3/7*7/2=3*7/(7*2)=3/2;
</span> 3) <span>2/3÷5/6=2*6/(3*5)=12/15=4/5
</span> 4) 8/15+3/2-4/5=8/15+0,6=8/15+3/5=(8+9)/15=17/15=1 2/15.
б)(-3)²+ (1/2)² ×3³=9+1*27/4=9+6 3/4=15 3/4.
x² +px - 18 = 0
x₁ = - 9
По теореме Виета :
x₁ * x₂ = - 18
x₂ = - 18 : x₁ = - 18 : (- 9) = 2
x₂ = 2
x₁ + x₂ = - p
- p = - 9 + 2
- p = - 7
p = 7