X=-3
because
-4x=21-9
-4x= 12 divide both sides
x=-3
Subtraction property of equality
2/3y = -6
2/3y × 3/2 = -6 × 3/2
multiplication property of equality
y = -9
<span>here we can use Pythogoras' theorem.
in right angled triangles the square of the hypotenuse is equal to the sum of the squares of the other 2 sides.
hypotenuse is 19 cm. One side is 13 cm and we need to find the length of the third side.
19</span>²<span> = 13</span>²<span> + X</span>²<span>
X - length of the third side
361 = 169 + X</span>²<span>
X</span>²<span> = 361 - 169
X</span>²<span> = 192
X = 13.85 the length of third side rounded off to the nearest tenth is 13.9 cm</span>
The first one, SAS Postulate
