(7a-3b)(-7a-3b)=
=-49a^2-21ab+21ab+9b^2=
=-49a^2+9b^2
<span>решите неравенство:
1. 5х - 2 < 0
</span><span><span>5х < 2
x < 2/5
x < 0,4
x∈(-oo;0,4)
</span>2. 4х + 5 > 2
</span><span><span>4х > 2-5
4x > -3
x > -3/4
x > -0,75
</span></span><span>x∈(-0,75;oo)
3. -5х - 8 ≤ 0
-1*(-5x-8) ≥ -1*0
5x + 8 ≥ 0
5x ≥ -8
x ≥ -8/5
x ≥ -1,6
</span><span>x∈[-1,6;oo)
4. 7х + 7 < 3х
</span><span>7х -3x < -7
4x < -7
x < -7/4
x < -1,75
</span><span><span>x∈[-oo;-1,75)
</span>
5. -4х - 8 < 7 - х</span>
-1*(-4x-8) > -1*(7 - x)
4х + 8 > x - 7
4x - x > -7 - 8
3x > -15
x > -5
<span> x∈(-5;oo) </span>